SecProbe.io

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 Document Miami International Holdings, Inc. 7 Roszel Road, Suite 1A Princeton, NJ 08540   December 9, 2025 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, D.C. 20549 Attention: Lulu Cheng Sandra Hunter Berkheimer David Lin Re: Miami International Holdings, Inc. Registration Statement on Form S-1 Filed December 9, 2025 File No. 333-292028 Ladies and Gentlemen: Pursuant to Rule 461 under the Securities Act of 1933, as amended, Miami International Holdings, Inc. (the “ Registrant ”) hereby requests acceleration of effectiveness of the effective date of its Registration Statement on Form S-1 (File No. 333-[•]) (the “ Registration Statement ”), so that it may become effective at 5:00 p.m., Eastern Standard Time on December 11, 2025, or as soon thereafter as practicable. The Registrant hereby authorizes Herbert Kozlov or Danielle Carbone of Reed Smith LLP, attorneys for the Registrant, to orally modify or withdraw this request for acceleration. The Registrant requests that it be notified of such effectiveness by telephone call to Herbert Kozlov at (212) 549-0241 or Danielle Carbone at (212) 549-0229. Sincerely, /s/ Thomas P. Gallagher Thomas P. Gallagher Chairman & Chief Executive Officer Miami International Holdings, Inc. cc: Barbara Comly, Esq. Miami International Holdings, Inc. Miami International Holdings, Inc. 7 Roszel Road, Suite 1A Princeton, NJ 08540   December 9, 2025 VIA EDGAR U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, D.C. 20549 Attention: Lulu Cheng Sandra Hunter Berkheimer David Lin Re: Miami International Holdings, Inc. Registration Statement on Form S-1 Filed December 9, 2025 File No. 333-292028 Ladies and Gentlemen: Pursuant to Rule 461 of the General Rules and Regulations under the Securities Act of 1933, as amended (the “ Act ”), the undersigned, for themselves and the several underwriters, hereby join in the request of Miami International Holdings, Inc. that the effective date of the above-referenced Registration Statement be accelerated so as to permit it to become effective at 5:00 p.m. Eastern Standard Time on December 11, 2025, or as soon thereafter as practicable. Pursuant to Rule 460 under the Act, the undersigned, as representatives of the several underwriters, wish to advise you that there will be distributed to each underwriter or dealer, who is reasonably anticipated to participate in the distribution of the securities, as many copies of the proposed form of preliminary prospectus as appears to be reasonable to secure adequate distribution of the preliminary prospectus. The undersigned advise that they have complied and will continue to comply with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended. [ Signature Page Follows ] Very truly yours, J.P. Morgan Securities LLC Morgan Stanley & Co. LLC Piper Sandler & Co. As representatives of the several underwriters J.P. MORGAN SECURITIES LLC By: /s/ Howard Chen Name: Howard Chen Title: Global Chair of Investment Banking MORGAN STANLEY & CO. LLC By: /s/ Jyri Wilska Name: Jyri Wilska Title: Managing Director PIPER SANDLER & CO. By: /s/ Demetrios Hadgis Name: Demetrios Hadgis Title: Managing Director [Signature Page to Request for Acceleration of Effectiveness]

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 Document Miami International Holdings, Inc. 7 Roszel Road, Suite 1A Princeton, NJ 08540   August 11, 2025   VIA EDGAR   U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, D.C. 20549 Attention: Lulu Cheng Sandra Hunter Berkheimer Re: Miami International Holdings, Inc. Registration Statement on Form S-1 Filed July 18, 2025 File No. 333-288767 Ladies and Gentlemen: Pursuant to Rule 461 under the Securities Act of 1933, as amended, Miami International Holdings, Inc. (the “ Registrant ”) hereby requests acceleration of effectiveness of the effective date of its Registration Statement on Form S-1 (File No. 333-288767) (the “ Registration Statement ”), so that it may become effective at 4:00 p.m., Eastern Standard Time on August 13, 2025, or as soon thereafter as practicable. The Registrant hereby authorizes Herbert Kozlov or Danielle Carbone of Reed Smith LLP, attorneys for the Registrant, to orally modify or withdraw this request for acceleration. The Registrant requests that it be notified of such effectiveness by a telephone call to Herbert Kozlov at (212) 549-0241 or Danielle Carbone at (212) 549-0229.  Sincerely, /s/ Thomas P. Gallagher Thomas P. Gallagher Chairman & Chief Executive Officer Miami International Holdings, Inc. cc: Barbara Comly, Executive Vice President, General Counsel and Corporate Secretary Miami International Holdings, Inc. Miami International Holdings, Inc. 7 Roszel Road, Suite 1A Princeton, NJ 08540   August 11, 2025   VIA EDGAR   U.S. Securities and Exchange Commission Division of Corporation Finance 100 F Street, NE Washington, D.C. 20549   Attention: Lulu Cheng Sandra Hunter Berkheimer Re: Miami International Holdings, Inc. Registration Statement on Form S-1 Filed July 18, 2025 File No. 333-288767 Ladies and Gentlemen: Pursuant to Rule 461 of the General Rules and Regulations under the Securities Act of 1933, as amended (the “ Act ”), the undersigned, for themselves and the several underwriters, hereby joins in the request of Miami International Holdings, Inc. that the effective date of the above-referenced Registration Statement be accelerated so as to permit it to become effective at 4:00 p.m. Washington D.C. time on August 13, 2025, or as soon thereafter as practicable. Pursuant to Rule 460 under the Act, the undersigned, as representatives of the several underwriters, wish to advise you that there will be distributed to each underwriter or dealer, who is reasonably anticipated to participate in the distribution of the securities, as many copies of the proposed form of preliminary prospectus as appears to be reasonable to secure adequate distribution of the preliminary prospectus. The undersigned advise that they have complied and will continue to comply with the requirements of Rule 15c2-8 under the Securities Exchange Act of 1934, as amended. [ Signature Page Follows ] Very truly yours, J.P. Morgan Securities LLC /s/ Apoorva Ramesh Apoorva Ramesh Vice President Morgan Stanley & Co. LLC /s/ Jyri Wilska Jyri Wilska Managing Director Piper Sandler & Co. /s/ Demetrios Hadgis Demetrios Hadgis Managing Director

December 20, 2024
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 11 to
Draft Registration Statement on Form S-1
Submitted November 27, 2024
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.
            Please respond to this letter by providing the requested information and either
submitting an amended draft registration statement or publicly filing your registration
statement on EDGAR. If you do not believe a comment applies to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.
            After reviewing the information you provide in response to this letter and your
amended draft registration statement or filed registration statement, we may have additional
comments. Unless we note otherwise, any references to prior comments are to comments in
our October 31, 2024 letter.
Amendment No. 11 to Draft Registration Statement on Form S-1
Financial Statements of Miami International Holdings, Inc. and Subsidiaries
Note 2. Summary of Significant Accounting Policies
Safeguarded Customer Digital Assets and Liabilities, page F-12
1.We note your response to prior comment 9 and continue to evaluate. We may have
further comments.
Note 12. Goodwill and Intangible Assets, page F-32
We note your response to prior comment 10. Please confirm whether or not the 2.

December 20, 2024
Page 2
following is true:
•There are no further performance obligations or services you are required to
provide in order to receive the remaining 375 million locked Pyth tokens and that
the only condition for unlocking is the passage of time.
•If you were to stop providing data to Pyth you would still receive the 375 million
locked Pyth tokens.
•Despite the fact that the locked Pyth tokens are not in the control or possession of
BSX and are held by another entity, you have a contractual right to the locked
tokens, and fully expect to receive them upon unlocking.
            Please contact Kate Tillan at 202-551-3604 or Michelle Miller at 202-551-3368 if you
have questions regarding comments on the financial statements and related matters. Please
contact Lulu Cheng at 202-551-3811 or Sandra Hunter Berkheimer at 202-551-3758 with any
other questions.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets
cc:Herbert F. Kozlov

October 31, 2024
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 10 to
Draft Registration Statement on Form S-1
Submitted September 20, 2024
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.
            Please respond to this letter by providing the requested information and either
submitting an amended draft registration statement or publicly filing your registration
statement on EDGAR. If you do not believe a comment applies to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response.
            After reviewing the information you provide in response to this letter and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amendment No. 10 to Draft Registration Statement on Form S-1
Prospectus Summary
Our Competitive Strengths
Focus on Innovation and Product Development, page 7
Please reconcile your statement here and on pages 43 and 178 that you "do not intend
to launch any crypto-related products or services in the near future on [your] national
securities exchanges which are regulated by the SEC (MIAX, MIAX Pearl, MIAX
Emerald or MIAX Sapphire)," with your statement on page 41 that you "anticipate
launching several new products in the future, including Bloomberg Indices Products,
futures and options on cryptocurrencies  and other financial products, subject to 1.

October 31, 2024
Page 2
regulatory approval ( emphasis added )."
Risk Factors
Risks Related to Owning a Clearing House
MGEX may incur large credit exposures on settlement days, page 33
2.We note your statement here that "[a]s a fully collateralized clearing house, MIAXdx
is not exposed to credit exposures on settlement (or any other) days, although it could
be exposed in the event it offers margin on cleared products in the future (upon CFTC
approval) (emphasis added) ." We also note your disclosure on page 6 that MIAXdx
intends, subject to CFTC approval, to incorporate an intermediated model and offer
margin on cleared products in connection with this change to an intermediated model.
Given your plan to transition MIAXdx to an intermediated model, please expand your
discussion of the credit exposure and other risks in the offering of margin on cleared
products.
Management's Discussion and Analysis of Financial Condition and Results of Operations,
page 96
3.As you have described on page 51, Pyth tokens are based on a highly volatile asset,
and fluctuation in the price of the Pyth tokens have in the past affected and may affect
your financial results in the future. As the volatility of crypto assets is inherent to your
operations, revenue generating activities, business strategy, and industry, it appears
that gain on sale and unrealized gain on derivative assets (pre-adoption of ASU 2023-
08) are part of your normal, recurring operations. Please tell us how this adjustment
complies with the guidance in Regulation G and question 100.01 of the Compliance
and Disclosure Interpretations for Non-GAAP Financial Measures.
Key Business Metrics, page 98
4.Refer to the section on options in the table. On page 101 you disclose that the $13.9
million decrease in options transaction and clearing fees was primarily the result of a
6.7% decrease in options market share and a 1.5% decrease in transaction and clearing
fees revenue per contract, partially offset by a 4.5% increase in options market ADV.
On page 98 you disclose total options revenue per contract (RPC) increased 12.2% for
the six months ended June 30, 2024, as well as increases in total market contracts and
market ADV. Please tell us and enhance future amendments to more fully explain
why the decline in MIH market share had a greater impact than these increases.
Cost of Revenues, page 118
5.We note that brokerage, clearing, and exchange fees increased $40.4 million, or
277.4%, for the year ended December 31, 2023, which you attribute to an increase in
clearing fees due to the acquisition of Dorman Trading in October of 2022. However,
the increase for the six months ended June 30, 2024, was only 22.7%. Please enhance
your disclosures in future amendments to clarify how the acquisition of Dorman
Trading impacted trends in your brokerage, clearing and exchange fees considering
the impact to operating income. Refer to Item 303(2)(i) of Regulation S-K.

October 31, 2024
Page 3
Business
Our Competitive Strengths
Proprietary MIAX Exchange Technology Platform, page 176
6.Please revise your discussions in this section to include MIAX Sapphire.
Our Growth Strategy
Increasing our international presence, page 182
7.We note you are currently replatforming the BSX trading system and expect to launch
a new BSX trading platform by April 2025. Please revise your disclosure to provide
more details about the replatforming, including without limitation any different
features or functions of the new trading platform.
Competition
Competition in Our Exchange Businesses, page 185
8.Please update your discussions in this section to include Green Impact Exchange,
LLC.
Note 2. Summary of Significant Accounting Policies
Safeguarded Customer Digital Assets and Liabilities, page F-12
In order to help us evaluate your crypto asset activities, please respond to the
following:
•Walk us through a typical physically settled crypto futures and options transaction
for which you provide clearing services. Your response should include a
discussion of the flow of fiat currency/cash and crypto assets from start-to-finish,
including all roles in the transaction.
•Tell us whether you clear crypto futures/options on behalf of entities that sell
physically settled contracts. If so, tell us whether you have a safeguarding
obligation as an agent. Explain the basis for your response.
•In addition to the information requested in the bullet above, clarify for us whether
you believe you have a safeguarding obligation, as an agent, with respect to
contracts issued by others for which you provide clearing services.
•You disclose that MIAXdx maintains custody of participant crypto-asset margin
deposits on behalf of participants to support their trading portfolio and crypto-
asset balances of participants held at the MIAXdx clearing house may be backing
orders, trades, or positions. Please clarify for us whether customers were required
to post margin equal to the full value of open physically settled positions.
•Tell us how customers access information about their crypto assets and whether or
not they may access that information through your platform, application, or
website.
•Explain to us the nature of your contractual relationships with all of the parties to
these transactions.
On page 5, you disclose that (i) MIAXdx has delisted all of its physically settled
products on its DCM and SEF and (ii) MIAXdx intends to no longer offer any
physically settled crypto products and is in the process of developing certain cash •9.

October 31, 2024
Page 4
settled products to trade on the MIAXdx DCM and SEF. Tell us whether the
delisting includes your DCO.
•Tell us whether or not you believe that delisting all physically settled crypto
options/futures relieves you of your obligation to recognize a safeguarding
obligation and if yes, tell us your reasoning.
Note 12. Goodwill and Intangible Assets, page F-77
10.Beginning on page 87, you disclose that in 2021, you entered into agreements with a
wholly owned subsidiary of Pyth Data Foundation to create a data feed and begin
publishing limited derived equities market data for certain symbols from MIAX Pearl
Equities on the Pyth Network. In exchange, you were granted the right to receive 500
million Pyth tokens, which were locked and restricted from trading, and which unlock
annually over a four-year period in equal tranches. Please respond to the following:
•Tell us the pertinent rights and obligations related to these agreements.
oTell us what you mean when you say that the tokens are locked and restricted
from trading. In your response, clarify whether the locked tokens are held by
an address controlled by you or held by an address controlled by another
entity.
oTell us whether you performed or are required to continue to perform
services to receive the tokens.
oTell us the basis for why the tokens initially unlocked annually.
•Tell us how you initially accounted for the transaction and why, citing the
accounting literature applied.
oTell us your consideration of whether the transaction should be accounted for
under ASC 606.
oTell us how you considered the initial accounting for the transaction when
accounting for the reminted Pyth tokens.
•With respect to your accounting for the remaining 375 million locked tokens to be
distributed to you, tell us why you believe these tokens meet the definition of a
derivative and cite the accounting literature applied and how you applied it to
your facts and circumstances.
oTell us who controls the remaining 375 million locked tokens and the basis
for your determination.
oTell us why the reminted tokens unlock annually starting in 2024 despite the
fact that the initial four-year period is now almost over.
•Tell us whether you have had any material arrangements to perform services,
other than the Pyth agreement above, in which the consideration you received (or
will receive) is non-cash consideration for the periods presented in your financial
statements.

October 31, 2024
Page 5
            Please contact Kate Tillan at 202-551-3604 or Michelle Miller at 202-551-3368 if you
have questions regarding comments on the financial statements and related matters. Please
contact Lulu Cheng at 202-551-3811 or Sandra Hunter Berkheimer at 202-551-3758 with any
other questions.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets
cc:Herbert F. Kozlov

United States securities and exchange commission logo
December 28, 2023
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 9 to
Draft Registration Statement on Form S-1
Submitted December 6, 2023
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR. If you do not believe a comment applies to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to this letter and your amended
draft registration statement or filed registration statement, we may have additional
comments. Unless we note otherwise, any references to prior comments are to comments in our
October 11, 2023 letter.
Amendment No. 9 to Draft Registration Statement on Form S-1
Risk Factors
Risks Relating to Crypto-Asset Custodial Arrangements
Crypto-asset custodial solutions and related technology, page 37
1.We note your response to prior comment 3 and related revised disclosure. Please revise to
further clarify the distinction between warm wallets and hot wallets. In this regard, we
note your disclosure that warm wallets primarily hold private keys online and accept
deposits automatically but require human involvement to initiate sweeps to hot wallets or
cold wallets, whereas hot wallets primarily hold private keys online but require human
involvement to initiate withdrawals. In particular, it is unclear whether the only permitted

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Thomas P. Gallagher
Miami International Holdings, Inc.
December 28, 2023
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withdrawals from warm wallets are sweeps to hot or cold wallets, and whether hot wallets
also accept deposits automatically.
Risks Related to Legal and Regulatory Matters
Regulatory action adversely affecting proprietary products, page 50
2.We note your response to prior comment 1 and that absent the issuance of a New
Exemptive Order from the SEC, the SPIKES Futures product will cease trading on MGEX
at close of trading on December 29, 2023. We also note your disclosure on page 172 that
trading on the NYSE Arca for the shares of SPKX and SPKY was suspended at the close
of trading on November 14, 2023, and each fund ceased operations, liquidated its assets
and distributed the liquidation proceeds to shareholders on November 27, 2023. Please
revise to describe any impact these cessations have had or may have on or disruption to
your business or financial condition.
Industry Overview
U.S. Futures, Options on Futures and Swaps Markets, page 155
3.We note your disclosure here and elsewhere that MGEX serves as the exclusive venue for
the clearing of two physically-settled Bitcoin futures contracts and one option on a futures
contract listed for trading on the Bitnomial Exchange (a Bitcoin derivatives exchange).
We also note that CFTC recently approved an order granting Bitnomial Clearinghouse,
LLC registration as a DCO under Section 5b of the Commodity Exchange Act. Please
update your disclosure to include this recent development.
4.We note your disclosure here and elsewhere that investors onboard directly with the
LedgerX clearing and trading platforms and not through an FCM. We also note the
CFTC's recent approval of a rule proposing regulations to provide protections for clearing
member funds and assets held by a DCO. Please update your disclosure here and in the
risk factors section to include this recent development.
Underwriting, page 275
5.Please revise your disclosure to confirm that the underwriters and their affiliates have only
engaged in, and will only engage in, such activities in accordance with the limitations and
restrictions of Rules 101 and 102 of Regulation M.

 FirstName LastNameThomas P. Gallagher
 Comapany NameMiami International Holdings, Inc.
 December 28, 2023 Page 3
 FirstName LastName
Thomas P. Gallagher
Miami International Holdings, Inc.
December 28, 2023
Page 3
            Please contact Kate Tillan at 202-551-3604 or Michelle Miller at 202-551-3368 if you
have questions regarding comments on the financial statements and related matters. Please
contact Lulu Cheng at 202-551-3811 or Sonia Bednarowski at 202-551-3666 with any other
questions.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets
cc:       Herbert F. Kozlov

United States securities and exchange commission logo
October 11, 2023
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 8 to
Draft Registration Statement on Form S-1
Submitted September 18, 2023
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR. If you do not believe a comment applies to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to this letter and your amended
draft registration statement or filed registration statement, we may have additional comments.
Unless we note otherwise, any references to prior comments are to comments in our August 28,
2023 letter.
Amendment No. 8 to Draft Registration Statement on Form S-1
Prospectus Summary
Our Company, page 1
1.Refer to your response to comment 8.  We note your disclosure on page 1 that
"[y]our portfolio of proprietary products, which are products licensed to [you] for
exclusive listing on [y]our exchanges, currently consists of the SPIKES Volatility
products," which is the first time you discuss this product in the registration statement.
Please summarize the Spikes Decision here or include a cross-reference to your disclosure
regarding the SPIKES Decision.  In this regard, we note your summary of the Spikes
Decision on pages 6 and 7.  In addition, please revise your risk factor disclosure on page

 FirstName LastNameThomas P. Gallagher
 Comapany NameMiami International Holdings, Inc.
 October 11, 2023 Page 2
 FirstName LastNameThomas P. Gallagher
Miami International Holdings, Inc.
October 11, 2023
Page 2
52 to disclose the revenue you earn from the SPIKES Futures products.
Summary Consolidated Financial Data, page 19
2.Please tell us why the table at the top of page 20 includes columns for fiscal 2021 and
2020 pro forma information and not just the latest year and interim period and comparable
prior interim period.
Risk Factors
Risks Relating to Crypto-Asset Custodial Arrangements
Crypto-asset custodial solutions and related technology, page 38
3.Refer to your response to comment 7.  Please revise to clarify whether “warm wallets”
require human involvement to accept deposits as well as initiate withdrawals.
Unaudited Pro Forma Condensed Combined Financial Information, page 82
4.We note your response to comment 12 and that pro form adjustment AA related to
acquisition of Ledger X LLC for the period ending June 30, 2023 is an income tax benefit
of $3.5 million, whereas for the year ended December 31, 2022 your pro forma adjustment
AA is an income tax expenses of $.132 million.  Please revise to explain the basis for
change in trends of the income tax adjustments, including changes in underlying
assumptions, e.g. tax rates.  Refer to Rule 11-02(a)(8) of Regulation S-X.
Management's Discussion and Analysis of Financial Condition and Results of Operations
Contractual Obligations, page 146
5.We acknowledge your response to comment 14 and related prior comment responses.  The
one-time cash bonuses paid to directors based on the length of service appears to be part
of your normal compensation structure elected by you to drive recurring operating results
as contemplated in Questions 100.01 and 102.09 of the C&DI on non-GAAP measures.
Please remove this adjustment.  Further, we are unable to locate the revised disclosure in
footnote 2 on pages 100, 114 and 129 of the amended draft registration statement with
reference to the senior secured loan agreement as noted in your response.
Business
Our Markets
U.S. Futures, Options on Futures and Swaps
Dorman Trading, page 170
6.Refer to your response to comment 3.  We note your disclosure on page 33 that states that
"[t]he settlement process for physically settled crypto asset-related products will depend
on the product, which may result in additional risks to customers of Dorman Trading" and
your disclosure on page 171 that, in the future, Dorman Trading clients may have the
ability to trade other physically settled crypto asset-related future products.  Please revise

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 October 11, 2023 Page 3
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Thomas P. Gallagher
Miami International Holdings, Inc.
October 11, 2023
Page 3
to disclose the “additional risks” to customers of Dorman Trading that are associated with
the settlement process for physically settled crypto asset-related products.
Regulatory Environment and Compliance
CFTC Regulation - MGEX and LedgerX, page 194
7.Refer to your response to comment 17.  We note your disclosure that LedgerX accepts
Bitcoin and Ether crypto assets for the payment of withdrawal fees and that you intend to
convert Bitcoin and Ether received for the payment of withdrawal fees into fiat currency
other than a de minimis amount.  Please disclose how you intend to exchange the crypto
assets into fiat currency.
Underwriting, page 275
8.Refer to your response to comment 19.  We note your disclosure on page 276 that "in
connection with this offering, in accordance with the provisions of Regulation M, the
underwriters may engage in stabilizing transactions, which involve making bids for,
purchasing and selling shares of common stock in the open market for the purpose of
preventing or retarding a decline in the market price of the common stock."  Please revise
your disclosure as follows:
•Clarify which provisions of Regulation M are applicable to this offering;
•Identify the underwriters, or disclose when the underwriters or underwriting
syndicate will be determined and identified; and
•Clarify and explain what types of stabilizing transactions or short positions may be
undertaken, given the absence of a public market for your common stock.
9.Refer to your response to comment 19 and your disclosure on page 277 relating to penalty
bids.  Please revise to correctly identify Regulation M as under the Exchange Act, not the
Securities Act.  Please also explain how penalty bids would be imposed given the absence
of any other underwriters or underwriting syndicate or delete the sentence.
10.Refer to your response to comment 20.  As there is no exception in Regulation M for
ordinary course of business activities, please clarify the intent and purpose of
the paragraph on page 277 immediately preceding the Pricing of the Offering section or
delete the added paragraph.
Miami International Holdings, Inc. Financial Statements
Note 4. Revenue Recognition
Consideration payable to a customer, page F-21
11.We note your response to comment 23.  Please enhance your disclosures to clarify, if true,
that liquidity payments represent a distinct service accounted for as consideration payable
to a customer and are recorded separately as liquidity payments within cost of revenues in
the consolidated statement of operations in the period in which the payment is earned by
the customer and the payment is provided.

 FirstName LastNameThomas P. Gallagher
 Comapany NameMiami International Holdings, Inc.
 October 11, 2023 Page 4
 FirstName LastName
Thomas P. Gallagher
Miami International Holdings, Inc.
October 11, 2023
Page 4
Note 14. Customer Assets and Liabilities
Safeguarded Customer Digital Assets and Liabilities, page F-73
12.Please enhance your disclosure to clarify that safeguarded customer digital assets
represent crypto assets held on behalf of your customers.
Ledger X LLC Financial Statements
Note 2. Summary of Significant Accounting Policies
Adoption of SAB 121, page F-127
13.We acknowledge your response to comment 26.  On page F-128, you disclose that
in 2022, the U.S. dollar value of safeguarded customer digital assets on deposit in
LedgerX’s hot and warm wallets exceeded $10M on fifteen days in total.  However, in
your response you told us that for the period from January 1, 2022 through May 23, 2022,
LedgerX’s primary crime insurance policy limit was $7.5 million and during that period,
the U.S. dollar value of digital assets on deposit in the LedgerX warm and hot custodial
wallets exceeded $7.5 million on 60 separate days.  Please revise the disclosure to provide
the same information.
            Please contact Kate Tillan at 202-551-3604 or Michelle Miller at 202-551-3368 if you
have questions regarding comments on the financial statements and related matters. Please
contact Lulu Cheng at 202-551-3811 or Sonia Bednarowski at 202-551-3666 with any other
questions.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets
cc:       Herbert F. Kozlov

United States securities and exchange commission logo
August 28, 2023
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 7 to
Draft Registration Statement on Form S-1
Submitted July 28, 2023
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amendment No. 7 to Draft Registration Statements on Form S-1
Gatefold Graphics, page v
1.We note the substantial number of graphics in the gatefold, including performance
indicators without accompanying narrative disclosure. Please revise to ensure that any
graphics and accompanying text provide a balanced view of your company and that
graphics including metrics include cross-references to their respective discussion in the
prospectus. We note your disclosure in these graphics that describe your company as “best
trading platform,” "top 40 innovators in the capital markets," and other statements of
leadership. Please remove these references or revise to explain the basis and context of
these awards. For guidance, please refer to Securities Act Forms Compliance and

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 Comapany NameMiami International Holdings, Inc.
 August 28, 2023 Page 2
 FirstName LastName
Thomas P. Gallagher
Miami International Holdings, Inc.
August 28, 2023
Page 2
Disclosure Interpretation 101.02.
Prospectus Summary
Our Growth Strategy
Further Monetizing and Enhancing Our Data and Analytics Capabilities, page 10
2.We note your statements here and on page 172 that BSX has “recently begun publishing
MIAX Pearl Equities market data to the Pyth Network.”  Please reconcile such statements
with your press release dated September 21, 2021 announcing that BSX has commenced
publishing MIAX Pearl Equities market data to the Pyth Network as of such date or
advise.
Risk Factors, page 23
3.Refer to your response to comment 4.  On page 31, you state that "[t]he settlement process
for physically settled crypto asset-related products differs from cash settled crypto-related
product transactions in that these transactions are settled directly at the Bakkt Trust
Company LLC, a crypto-asset custodian chartered under New York banking law and
regulated by the New York Department of Financial Services (the “Bakkt Warehouse”),
which may result in additional risks to customers of Dorman Trading." Please revise to
disclose these "additional risks."
If a number of clearing members on MGEX, page 33
4.Please move the second paragraph in this risk factor to the immediately preceding risk
factor, as the discussion relates to settlement banks and not clearing members.
Risks Related To Owning A Clearing House
Settlement bank failures could pose both credit risks, page 33
5.We note your disclosure on page 33 that "[t]he size of the MGEX and LedgerX clearing
houses’ credit and liquidity exposures to their settlement may be quite significant . . . ."
Please revise to clarify your disclosure by adding the word “banks” after the word
“settlement” or advise.
Risks Relating to Our Ownership of LedgerX
The past, current and future operation of LedgerX, page 34
6.We note your disclosure on pages 35 and 197 that "LedgerX is responding to certain
requests for information and documents from the CFTC’s Division of Enforcement and
may come under additional regulatory scrutiny, requests or investigations in the future"
and that the requests relate to activities during the prior ownership of LedgerX by FTX.
Please revise to discuss in your Legal Proceedings section on page 182.

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Crypto-asset custodial solutions and related technology, including the LedgerX custodial
arrangements, page 35
7.Please revise to include a brief definition of "cold wallets," "warm wallets," and "hot
wallets."
Risks Related to Legal and Regulatory Matters
Regulatory action adversely affecting proprietary products exclusively licensed by us, page 48
8.Please update your disclosure here, on page 183 and throughout the filing in light of the
recent ruling by the United States Court of Appeals for the District of Columbia Circuit
relating to the SEC Order for SPIKES Futures (Cboe Futures Exchange, LLC v. SEC, 21-
1038 (D.C. Cir.)(Jul. 28, 2023)), including without limitation any impact on or disruption
to your product listings, business or financial condition, and the steps, if any, you will take
to seek other regulatory relief with respect to SPIKES futures listings.
There are significant regulatory hurdles to launching new crypto-related products, page 50
9.We note your disclosure on page 50 that "[a] number of enforcement actions and
regulatory proceedings have since been initiated against crypto-assets . . . ."  Please revise
to clarify, if true, that you are referring to issuers of crypto assets.
Changes to the legislative or regulatory environment may impose, page 52
10.Please update your disclosure here and on page 205 to reflect the most recent status of the
draft legislation that would provide a statutory framework for the regulation of crypto
assets.
Dilution, page 76
11.You disclose that your historical net tangible book value as of March 31, 2023 was
$(137.5) million and your historical net tangible book value per share was calculated
based on 96,175,702 shares of non-puttable outstanding common stock as of March 31,
2023.  Please show us how you determined that your historical net tangible book value per
share as of March 31, 2023 was $(1.16) per share of your common stock.
Unaudited Pro Forma Condensed Combined Financial Information, page 79
12.Please enhance your pro forma transaction accounting adjustments to disclose the
underlying calculations of the related adjustments.  Refer to Rule 11-02(a)(8) of
Regulation S-X.
13.Please enhance your disclosure of the (preliminary) purchase price allocation for the
LedgerX Acquisition of adjustments made to the latest financial statements included in
future amendments, e.g. cash and cash equivalents.

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Miami International Holdings, Inc.
August 28, 2023
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Management's Discussion and Analysis of Financial Condition and Results of Operations
Contractual Obligations, page 145
14.We acknowledge your response to comment 18.  Please respond to the following:
•Tell us whether your non-GAAP measure is as calculated by the debt covenant of
your senior secured loan agreement.
•Tell us how you considered the disclosures discussed in Question 102.09 of the
C&DI on non-GAAP measures.
•Tell us why you refer to your credit facility and not your senior secured loan
agreement in footnote 2 on pages 99, 113, and 128.
Business
Our Company, page 158
15.We note your statement on page 158 that you are a technology-driven leader in building
and operating “regulated finances” across multiple asset classes and geographies.  Please
revise your disclosure to clarify what you mean by "regulated finance."
Our Growth Strategy
Further monetizing and enhancing our data and analytics capabilities, page 172
16.Refer to your response to comment 24.  We note your statement that it is expected that
BSX may be reissued tokens, although no specific timeline for such reissuance has been
announced.  Please disclose how many tokens BSX has earned but not yet received.
Please also disclose whether you currently have any agreements with a third-party
custodian with respect to custody and storage of the PYTH tokens, and, if so, describe the
material terms of the agreement.  Also revise your risk factors section to describe the risks
of using a hot wallet as compared to a cold wallet.  In this regard, we note your disclosure
on page 36 that "[c]rypto-assets held held in cold, warm and hot wallets are also subject to
the risk of theft and cybersecurity attacks."
Regulatory Environment and Compliance
CFTC Regulation - MGEX and LedgerX, page 191
17.We note your disclosure on page 191 that LedgerX accepts Bitcoin and Ether crypto
assets for collateral and for the payment of fees.  Please disclose whether you intend to
hold the crypto assets for investment or convert them into fiat currency or other crypto
assets after receipt.  In addition, please disclose how and when you calculate the value of
the crypto assets used for payment of fees.
18.We note your disclosure on page 191 that during the contract lifecycle LedgerX exercises
control over crypto assets as it holds private keys to the hot wallet.  Please revise your risk
factors section to describe any risks and challenges related to the storage or custody of the
private keys granting access to the crypto assets, including without limitation the threat of
a cybersecurity breach.

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Miami International Holdings, Inc.
August 28, 2023
Page 5
Underwriting, page 267
19.Refer to your response to comment 13 in our letter dated September 6, 2022.  Please
revise your disclosures on pages 268 and 269 to remove the implication that Regulation M
distribution would potentially continue and that the applicable restricted period may not
have ended.  In addition, please clarify the scope of any possible “stabilizing” activities.
20.We note your disclosures relating to the various activities the underwriters and their
affiliates are engaged in, have performed, or may from time to time perform.  Please
revise your disclosure here and throughout to confirm that the underwriters and their
affiliates have only engaged in, and will only engage in, such activities in accordance with
the limitations and restrictions of Rules 101 and 102 of Regulation M.
Miami International Holdings, Inc. Financial Statements
Consolidated Balance Sheets, page F-4
21.We acknowledge your response to comment 27.  Based on your disclosure, the
extinguishment of the liability associated with outstanding puttable common stock is a key
aspect of this offering.  Please tell us how you considered Rule 5-02.27 of Regulation S-X
and ASR 268 in your presentation.
Consolidated Statements of Operations, page F-5
22.In response to comment 28 you told us that you only include transaction-based expenses
in the line item described as cost of revenues and this amount is used to determine the line
item revenues less cost of revenues.  Please revise so that the description of the line items
is consistent with its components, such as labeling the line items transaction-based
expenses and total revenues less transaction-based expenses.
Note 4. Revenue Recognition
Consideration Payable to a Customer, page F-20
23.We acknowledge your response to comment 31. Your response did not fully address our
comment.  Please respond to the following:
•In your response you told us that liquidity payments are determined based on
published rates that you may update.  Tell us how you determine the published rates.
Tell us about your pricing strategy where liquidity payments result in inverted
pricing.
•You told us that liquidity payments do not exceed the fair value of the distinct
services provided by your customers but you did not explain the basis for your
response.  Tell us why.  Tell us whether you performed a fair value measurement for
those services and, if you did, the results.  Specifically address liquidity payments
that result in inverted pricing.
•Under ASC 606-10-32-26, if the amount of consideration payable to a customer
exceeds the fair value of the distinct good or service that you receive from the

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Page 6
customer, then you should account for the excess as a reduction of the transaction
price.  Further, if you cannot reasonably estimate the fair value of the good or service
received from the customers, you should account for all of the consideration payable
to the customer as a reduction of the transaction price.  Tell us how you considered
this guidance in your accounting for the liquidity payments, including those that
result in inverted pricing.
Note 11. Goodwill and Intangible Assets, page F-28
24.We acknowledge your response to comment 33.  We note that you account for
your cryptocurrencies as intangible assets.  Tell us how you considered the guidance in
ASC 350-30-45-2 to classify impairment of intangible assets within continuing
operations.  In light of the classification requirement, tell us your consideration for
reclassifying charges for impairment of cryptocurrencies within operating expenses.
LedgerX LLC, page F-118
25.We note your disclosure on page 195 that participant crypto-asset margin deposits are
maintained in LedgerX’s participant digital wallets and are not commingled with
LedgerX’s proprietary crypto-assets.  Please enhance your disclosures to clarify what
proprietary crypto-assets LedgerX holds for the periods presented.  Please also enhance
your summary of significant accounting policies to disclose the nature and accounting of
LedgerX other current assets and other assets for the periods presented.
Note 4. Participant Margin Deposits, page F-126
26.We note that in conjunction with LedgerX clearing house activities as the central
counterparty to settlement, customer digital assets held as collateral are recognized as
safeguarded customer digital assets offset with safeguarded customer digital asset
liabilities.  Please address the following:
•Tell us and enhance your disclosures to clarify the legal and accounting ownership of
the custodied digital assets upon receipt, prior to, at settlement and after settlement.
Refer to SAB 121.
•Tell us and enhance your disclosures to clarify the basis of your determination to
recognize a safeguarding crypto-asset liability and offsetting asset instead of
recognition of custodied digital assets and offsetting liability to return those digital
assets since during the contract lifecycle you exercise control over crypto-assets
(page 191) and you control participant accounts held at BitGo Trust on behalf of
LedgerX.  Refer to SAB 121.
•Tell us and enhance your disclosures of how you monitor and evaluate the
availability of the BitGo Trust $250 million insurance policy that applies to all BitGo
Trust balances against your potential crypto-asset losses.
•Tell us and disclose how many days during the periods presented have crypto-assets
in warm or hot wallets exceeded the total amount of your primary crime insurance
policy and were swept into BitGo Trust cold wallets.

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•Tell us and enhance our disclosures to clarify if you have right to the increases in fair
value of customer digital asset

United States securities and exchange commission logo
June 15, 2023
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 6 to
Draft Registration Statement on Form S-1
Submitted April 7, 2023
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amendment No. 6 to Draft Registration Statement on Form S-1
Prospectus Summary
Our Company, page 1
1.We note that you intend to launch a fourth Taker-Maker U.S. options exchange in early
2024.  Please disclose what crypto assets, if any, will be or are expected to be traded on
this platform.

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 June 15, 2023 Page 2
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Thomas P. Gallagher
Miami International Holdings, Inc.
June 15, 2023
Page 2
Our Growth Strategy
Expanding into the emerging, regulated cryptocurrency and digital asset markets, page 8
2.Please revise your disclosure on page 9 relating to the Bermuda regulatory environment to
clarify that any crypto asset or crypto asset products launched on BSX would not be made
available to U.S. persons and that you would, in consultation with counsel, implement
appropriate procedures to ensure that any investors in these products meet the eligibility
requirements of such products. In this regard, we note your disclosure on page 136.
The Offering, page 14
3.Please enhance your disclosure here as well as on pages 68, 70, and 207 to clarify what
happens to the outstanding options to acquire preferred stock and non-voting common
stock upon the IPO.
Risk Factors, page 21
4.Refer to your added disclosure on page 155.  Please add a risk factor addressing the risks
related to conducting settlement processes for physically settled crypto asset-related
products through the Bakkt Warehouse.
Risks Related to Our Growth Strategy
We intend to opportunistically pursue potential acquisitions and strategic alliances, page 34
5.We note your disclosure that you intend to opportunistically pursue potential acquisitions.
Please tell us whether you have any current plans, arrangements or agreements for any
acquisitions.  In this regard, we note media reports that you are seeking to acquire
LedgerX, which is being sold in FTX's bankruptcy proceedings.
Risks Related to Legal and Regulatory Matters
There are significant regulatory hurdles to launching new crypto-based products, page 43
6.We note your disclosure on pages 45, 136 and 153 that you could be subject to judicial or
administrative sanctions for acting as a broker, dealer, or national securities exchange
without appropriate registration. Please revise to disclose that you could be subject to
judicial or administrative sanctions for acting as a clearing agency without appropriate
registration.
Changes to the legislative or regulatory environment may impose new or unanticipated burdens,
page 45
7.Please revise your disclosure here and on page 159 to clarify the status of SEC proposals
as proposed rulemakings and not legislation.

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Miami International Holdings, Inc.
June 15, 2023
Page 3
Our exchanges have self-regulatory obligations that may create conflicts of interest, page 48
8.Please revise your disclosure to identify which category of U.S. exchanges are responsible
for identifying possible violations of the securities laws, and whether such responsibilities
extend to derivatives transactions.
Risks Related to This Offering and Our Common Stock
Our amended and restated certificate of incorporation contains provisions that set ownership and
voting limitations, page 55
9.Please revise your disclosure to clarify to whom prior notice with respect to ownership
and exercise of voting power of your capital stock must be given.
Capitalization, page 67
10.We note that your offering includes shares of common stock by selling shareholders.
Please enhance your disclosures to explain how the conversion of all the outstanding
shares of Series B convertible preferred stock and nonvoting common stock will be
effected, is probable and clarify the underlying terms of these issuances as disclosed in
Note 16. Equity, beginning on page F-35 as necessary.
11.Your total capitalization agrees to the total amount of your liabilities and stockholders'
deficit as shown on page F-3, and not your capitalization, and does not foot.  Please revise
so that the capitalization table properly foots.
Unaudited Pro Forma Condensed Combined Statement of Operations, page 73
12.Please revise so that the amounts shown for your historical weighted-average shares and
income per share agree to page F-4.  Since we note that the pro forma weighted-average
shares agree to your historical amounts on page F-4, tell us whether the pro forma
weighted-average shares are based on the weighted-average number of shares outstanding
during the period adjusted to give effect to the number of shares issued to consummate the
transaction as if the shares were outstanding as of the beginning of the period presented.
Refer to Item 11-02(a)(9)(ii).
Note 2. Purchase Price Allocation, page 74
13.Please provide a table showing the components of the total consideration transferred and
disclose how they were measured.  For the contingent consideration, also provide any
disclosures required by Item 11-02(a)(11)(ii)(A) of Regulation S-X.
14.Since you disclose that the assets and liabilities assumed are reflected at their preliminary
estimated fair values, please include a prominent statement that the accounting is
incomplete and provide any disclosures required by Item 11-02(a)(11)(ii)(B).

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Notes to Pro Forma Condensed Combined Information
Note 1. Basis of Presentation, page 74
15.You disclose that the pro forma financial statements reflect events that are directly
attributable to the combination, factually supportable, and expected to have a continuing
impact on the combined results.  Please revise your presentation consistent with the recent
amendment to Item 11-02(a)(6)(i)(B) of Regulation S-X. Refer to Release 33-10786.
Management's Discussion and Analysis of Financial Condition and Results of Operations
Our Business Model
Futures, page 77
16.Please tell us why you disclose that Dorman Trading will be included in the Futures
segment.  Since you acquired Dorman Trading in October 2022, disclose what
segment Dorman Trading is included in for 2022.
Results of Operations
Comparison of the Years Ended December 31, 2022 and 2021, page 83
17.Please revise your disclosures to clearly reflect that adjusted revenues less cost of revenue
is a non-GAAP measure. Refer to Question 100.05 of the Compliance and Disclosure
Interpretations on Non-GAAP Financial Measures.
18.Please tell us how the adjustments for impairment of Pyth tokens, the provision for CAT
notes receivable, and cash bonuses to directors are consistent with Item 10(e)(1)(ii)(B) of
Regulation S-K as these appear to be elective, cash based, necessary operating costs and
Pyth tokens were received in exchange for data services provided. Refer to Questions
100.01 and 102.03 of the Compliance and Disclosure Interpretations on Non-GAAP
Financial Measures.
19.Where a material change in a line item is attributed to two or more factors, including
offsetting factors, the contribution of each identified factor should be described in
quantified terms, if reasonably practicable.  Please revise your disclosures accordingly.
Refer to Item 303(a) of Regulation S-K and Section III.D of SEC Release No. 33-6835.
Key Business Metrics, page 86
20.You disclose that three customers accounted for a significant amount of your total
revenues during the years ended December 31, 2022, 2021 and 2020.  Please disclose the
level of recurring customers and or revenues, for the periods presented.
Critical Accounting Policies and Estimates
Common Stock Valuation, page 116
21.Once you have an estimated offering price or range, tell us the reasons for any differences
between recent valuations of your common stock leading up to the IPO and the estimated

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offering price.  Please discuss with the staff how to submit your response.
Our Competitive Strengths
Successful History of M&A and Strategic Investments, page 133
22.Please tell us whether you continue to have investments in Lukka, Inc., MEEG Holdings
Limited, Vesica Technologies, Inc., Stratifi Technologies, Inc., Diamond Standard Inc.
and OptionsAI, Inc. To the extent that you continue to have these investments or others,
and to the extent that such investments are material, please disclose your holdings in such
companies as well as the material terms of any agreements you have with such companies.
Our Growth Strategy
Expanding into the emerging, regulated cryptocurrency and digital asset markets, page 135
23.We note your disclosure here that you believe you have a unique opportunity to develop
and launch regulated products in the crypto assets markets and that, in the near term, you
plan to launch cash-settled futures contracts on MGEX on certain crypto assets such as
Bitcoin.  Please expand your disclosure here and in your risk factors section to provide
examples of how the bankruptcies of FTX and other companies in the crypto asset
markets have brought increased scrutiny to the crypto asset industry and how such
scrutiny may impact your plans to develop and launch products in the crypto asset
markets.  For example, describe any risks related to the assertion of jurisdiction by U.S.
and foreign regulators and other government entities over crypto assets and crypto asset
markets, and any material pending crypto-related legislation or regulation that has or may
impact such plans to launch new products.
Further monetizing and enhancing our data and analytics capabilities, page 136
24.Refer to your response to comment 15, and please disclose the substance of your response
in your amended registration statement.  Also disclose when BSX will receive its earned
Reward PYTH Tokens and how many tokens BSX has earned but not yet received.  In
addition, we note that BSX plans to hold any replacement PYTH tokens that it receives
for the now-inaccessible PYTH tokens, as well as any PYTH tokens it receives in
exchange for data provided to the PYTH network in a non-FTX replacement account or
hot wallet.  Please disclose whether you currently have any agreements with a third-party
custodian and, if so, please describe the material terms of the agreement.  Also briefly
describe the risks of using a hot wallet in your risk factors section.

Regulatory Environment and Compliance
U.S. Regulation - Dorman Trading, page 154
25.We note your responses to prior comments 14 and 17.  Please disclose comparable
Dorman crypto-related futures activity, including total contracts traded, open interests, the
notional value and your exposure to loss.

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 June 15, 2023 Page 6
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Miami International Holdings, Inc.
June 15, 2023
Page 6
Experts, page 228
26.Please tell us why you do not make reference to Ryan & Juraska LLP as experts.
Miami International Holdings, Inc.
Consolidated Balance Sheets, page F-3
27.Please revise the line items on the balance sheets for the following:
•Your largest liability, puttable common stock, should be shown separately and not
included within the line item other non-current liabilities.
•Your preferred stock should be labeled to show that it is convertible.
Consolidated Statements of Operations, page F-4
28.Please tell us whether costs included in cost of revenues represent all of your costs of
revenue, including compensation, depreciation, etc. or just your transaction-based
expenses.  Refer to SAB Topic 11.B.
Note 3. Business Combinations
Dorman Trading Acquisition, page F-16
29.Please respond to the following:
•Disclose the date used to value the consideration.  Refer to ASC 805-30-50-1(b).
•Disclose the method used to determine the fair value of the common stock issued.
Refer to ASC 805-30-50-1(b)(4).
Unaudited Pro Forma Financials, page F-18
30.Please reconcile for us the difference between the pro forma net income for 2022 on page
F-18 with the pro forma net income for 2022 on page 73.
Note 4. Revenue Recognition
Consideration Payable to a Customer, page F-20
31.We acknowledge your response to comment 18.  On page 80, you disclose that you offer
liquidity payments that exceed or are higher than transaction fees resulting in inverted
pricing to attract order flow.  Please address the following:
•Tell us how liquidity payments are determined and or calculated and whether the
liquidity payments exceed the fair value of the distinct goods or services provided to
you by your customer.
•Tell us if you account for liquidity payments that result in inverted pricing differently
than liquidity payments that are less than transaction fees.
Refer to ASC 606-10-32-25 and 32-26.
32.You disclose that liquidity payments are accounted for as consideration payable to a
customer and reduce revenue in the period in which the rebate is earned by the customer
and the payment is provided.  On page 79, you disclose that liquidity payments are

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Miami International Holdings, Inc.
June 15, 2023
Page 7
classified within cost of revenues in the consolidated statement of operations and you
classify liquidity payments within cost of revenues in the consolidated statements of
operations on page F-4.  Please reconcile and revise your disclosures accordingly.
Note 11. Goodwill and Intangible Assets, page F-27
33.You disclose that BSX received Pyth tokens in exchange for certain data provided by
BSX to the Pyth Network. Please tell us why you classified the impairment of the Pyth
tokens within non-operating expenses since payment for services is part of your operating
activities.
Note 14. Fair Value Measurement
Fair Value of Assets and Liabilities, page F-31
34.Refer to the table at the top of page F-32.  Please tell us the significant factors that caused
your common stock price to decline from $12.89 in 2021 to $9.92 in 2022.
Note 16. Equity
Common Stock, page F-35
35.Please respond to the following:
•Disclose the terms of the non-voting common stock, including whether and how the
stock may become voting common stock.  Refer to ASC 505-10-50-3.
•You interchangeably refer to warrants and common stock issued under your ERP
programs as "redeemable" and or "puttable". Clarify whether the redeemable
common stock is the puttable common stock related to the ERP p

United States securities and exchange commission logo
January 17, 2023
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 5 to
Draft Registration Statement on Form S-1
Submitted December 22, 2022
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amended Draft Registration Statement submitted December 22, 2022
General
1.Please disclose any significant crypto asset market developments material to
understanding or assessing your business, financial condition and results of operations
since your last reporting period, including any material impact from the price volatility of
crypto assets.
Cover page
2.Please disclose on the cover page and in Our Company on page 1 limitations on
shareholder voting rights, including the 40% limitation on share ownership.

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 Comapany NameMiami International Holdings, Inc.
 January 17, 2023 Page 2
 FirstName LastNameThomas P. Gallagher
Miami International Holdings, Inc.
January 17, 2023
Page 2
Risk Factors, page 20
3.To the extent material, please discuss any reputational harm you may face in light of the
recent disruption in the crypto asset markets.  For example, discuss how market conditions
have affected how your business is perceived by customers, counterparties, and regulators,
and whether there is a material impact on your operations or financial condition.
4.Please describe any material risks to your business from the possibility of regulatory
developments related to crypto assets and crypto asset markets.  Identify material pending
crypto legislation or regulation and describe any material effects it may have on your
business, financial condition, and results of operations.
5.Please describe any material risks you face related to the assertion of jurisdiction by U.S.
and foreign regulators and other government entities over crypto assets and crypto asset
markets.
6.To the extent material, please describe any gaps your board or management have
identified with respect to risk management processes and policies in light of current crypto
asset market conditions as well as any changes they have made to address those gaps.
7.To the extent material, please describe any of the following risks from disruptions in the
crypto asset markets:
•Risk from depreciation in your stock price.
•Risk of loss of customer demand for your products and services.
•Financing risk, including equity and debt financing.
•Risk of increased losses or impairments in your investments or other assets.
•Risks of legal proceedings and government investigations, pending or known to be
threatened, in the United States or in other jurisdictions against you or your affiliates.
•Risks from price declines or price volatility of crypto assets.
Business, page 125
8.To the extent material, please discuss whether any of the recent bankruptcies of
companies in the crypto asset markets and the downstream effects of those bankruptcies
have impacted or may impact your business, financial condition, customers and
counterparties, either directly or indirectly.
9.To the extent material to an understanding of your business, please describe any direct or
indirect exposures to other counterparties, customers, custodians, or other participants in
crypto asset markets known to:
•Have filed for bankruptcy, been decreed insolvent or bankrupt, made any assignment
for the benefit of creditors, or have had a receiver appointed for them.
•Have experienced excessive redemptions or suspended redemptions or withdrawals
of crypto assets.
•Have the crypto assets of their customers unaccounted for.
•Have experienced material corporate compliance failures.

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U.S. Futures, page 128
10.We note your response to comments 3 and 4, as well as disclosure updates on pages 130-
131.  You state that Dorman earns commission fees related to crypto products.
Disclosures such as those on pages 30, 126, and 130 say that Dorman provides execution
and clearing services to customers.  However, disclosures on page 130 say that physically
settled crypto asset-related products offered to Dorman clients are cleared and settled
directly by Bakkt at the Bakkt warehouse.  In addition, your response to comment 4 and
disclosures on page 131 say that you do not transact in or execute crypto asset
transactions.  Please address the items below.
•Clarify your disclosures to explain what you mean when you say that cash and
physically settled crypto-asset related futures products are “offered” to Dorman
customers, including what roles and responsibilities Dorman has related to such
products.
•Specify for us, and revise your disclosures to indicate, who executes Dorman
customers’ crypto asset-related transactions and what role, if any, Dorman plays in
this activity.
•Tell us, and revise your disclosures to identify, the specific service or services
provided by Dorman that generate commission fees for crypto related products.
•Also provide us with an accounting analysis detailing your consideration of revenue
recognition accounting guidance for revenues related to crypto products, including
but not limited to your determination of your customers as defined by ASC
606, identification of your performance obligations, and consideration of timing of
your recognition of related revenue.
11.We note your response to comment 4 and related disclosure update on page 131, including
that Dorman’s business does not involve custody of crypto assets and that delivery of
physical crypto assets are made directly to Dorman Trading clients.  Please revise your
disclosures to further clarify this process, such as by indicating where accounts receiving
the crypto assets would be held, and any relationship Dorman has, if any, to such
accounts.
12.We note the response to comment 5.  We also note the disclosure, in the risk factor on
page 40, that Dorman Trading’s activities include the safeguarding of client assets.  Please
address how this disclosure is consistent with the response to comment 5 and/or indicate
the nature of the client assets for which the activity of safeguarding assets is provided.
13.We note your disclosures on page 130 regarding margin related to Dorman Trading's
business.  Please revise your disclosures, here or elsewhere as appropriate, to address how
you monitor and manage risks of Dorman's involvement in crypto-based products, similar
to the level of disclosure you provide for MGEX on pages 153-154 (e.g., discussion of
any stress testing and scenarios, margin methodology detail, considerations of customer or
Bakkt default, bankruptcy, or similar financial exposures, etc.).
14.We note your disclosure on page 130 that Dorman's business involves establishing and

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carrying open positions for clients on regulated futures exchanges and that Dorman must
post and maintain margin or credit support.  For the periods presented, please quantify for
us:
•the level of open crypto-related positions for clients established and carried by
Dorman;
•volume, maximum volume, and trending for financially and, separately, physically
settled crypto asset-related product transactions related to Dorman;
•the amount of your financial exposure associated with crypto-related transactions
associated with Dorman; and
•any losses incurred by you as a result of crypto-related transactions related to
Dorman.
Our Growth Strategy
Further monetizing and enhancing our data and analytics capabilities, page 137
15.Please briefly describe the terms of publishing MIAX Pearl Equities market data on the
Pyth Network, including how BSX earns PYTH tokens for the data it provides.
Also describe the characteristics of the PYTH tokens, and BSX's plans and policies
relating to PYTH tokens, including whether BSX stakes the tokens on the
PYTH Network.  Address any risks attendant to the publication of data on the Pyth
Network, the characteristics of the PYTH tokens, BSX's policies related to the use of the
PYTH tokens and the custody arrangements for the PYTH tokens.  In addition, disclose
where BSX stores its PYTH tokens, and, to the extent that BSX uses a third-party
custodian for the tokens, describe BSX's custody procedures and arrangements by
identifying its third-party custodians and the material terms of the agreements, including:
•What portion of the tokens are held in hot wallets and cold wallets.
•The geographic location where the tokens are held in cold wallets.
•Whether any auditors or other persons are responsible for verifying the existence for
the tokens held by third-party custodians.
•Whether any insurance providers have inspection rights associated with the digital
assets held in storage.
•A description of the custodian's insurance and the degree to which such policies
provide coverage for the loss of BSX's PYTH tokens.
16.We note your response to comment 4 and disclosure on pages 9 and 137 that the value of
tokens held by BSX was immaterial as of September 30, 2022.  Please:
•quantify for us the number and value of the tokens held by BSX;
•clarify for us whether all of these are PYTH tokens and, if not, specify what other
tokens are held; and
•explain to us how you valued these tokens.
CFTC Regulation - MGEX, page 153
17.We note your disclosure on page 154 of total monthly volume of contracts traded on
Bitnomial Exchange.  Please revise your disclosures to additionally quantify dollar

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volumes associated with these contracts and the amount of your financial exposure
associated with them.
Miami International Holdings, Inc. and Subsidiaries
Notes to Consolidated Financial Statements
Note 4. Revenue Recognition
Transaction and clearing fees, page F-14
18.We note you account for rebates paid for certain customer transactions as consideration
payable to a customer and you record them separately as transaction rebates, which are
classified within cost of revenue in the consolidated statement of operations. Please
provide us with an accounting analysis explaining what consideration you have given to
ASC 606-10-32-25 and supporting your conclusions and accounting treatment of these
rebates.
Dorman Trading, LLC
Notes to Financial Statements
Summary of Significant Accounting Policies, page F-80
19.Please revise to provide an accounting policy which defines and addresses payables to
"customers" and "noncustomers" and indicate if these amounts relate to any transaction
rebate activity. In addition, clarify for us where any related expense is reflected in the
income statement.
Revenue Recognition, page F-80
20.Please revise to disclose the components of “other client revenue” as well as the
associated accounting for each of the components for the periods presented. Refer to ASC
606-10-50.
            You may contact Cara Lubit at 202-551-5909 or Marc Thomas at 202-551-3452 if you
have questions regarding comments on the financial statements and related matters.  Please
contact Sonia Bednarowski at 202-551-3666 or J. Nolan McWilliams, Acting Legal Branch
Chief, at 202-551-3217 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets

United States securities and exchange commission logo
October 28, 2022
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 4 to
Draft Registration Statement on Form S-1
Submitted October 25, 2022
CIK No. 0001438472
Dear Thomas P. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amendment No. 4 to Draft Registration Statement on Form S-1
Business
Dorman Trading, page 121
1.We note your acquisition of Dorman Trading, LLC (Dorman) on October 19, 2022.
Please provide us with your significance test analysis performed in consideration of
requirements under Article 11 and Rule 3-05 of Regulation S-X.  In addition, ensure that
pro forma disclosures contemplated under ASC 805 are included in a future amendment to
the extent that they are required for periods then presented.
2.Please quantify the total cash and equity consideration to be paid by you to

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acquire Dorman Trading.
3.Please tell us what crypto asset-related products are offered, executed, and / or
cleared through Dorman and what responsibilities Dorman has with respect to related
transactions.  Your response should address but not be limited to the following:
•tell us which of these crypto-related products physically settle and have traded to
date, and quantify volume trends;
•explain what types of revenue are or could be generated for you from these products,
and quantify revenue trends for them;
•clarify whether Dorman fulfils any crypto-related orders using its own inventory,
credit, or cash; and
•describe any differences with regards to settlement and delivery processes for crypto-
related transactions executed, cleared, or otherwise facilitated by Dorman as
compared to what is currently disclosed for your other entities.
4.Please clarify for us whether the business activities of Dorman result in changes related to
crypto asset processes, such as but not limited to whether any of your entities now or will
be expected to: (i) have control over crypto assets at any time; (ii) have access to private
keys of crypto assets at any time; (iii) transact in crypto assets or execute crypto asset
transactions; (iv) accept crypto assets as collateral or other forms of payment (and, if so,
the types of assets accepted and under what circumstances); (v) custody crypto assets; or
(vi) have crypto assets moving through your systems at any point.
5.Please tell us how you considered whether your acquisition of Dorman and post-
acquisition business changes your conclusion that Staff Accounting Bulletin 121 does not
apply to you.  To the extent that each aspect is applicable, your response should include,
but not be limited to, addressing your involvement in ongoing reporting and customer
service of users' crypto asset holdings; your ability (or lack thereof) to suspend users'
access to their crypto holdings or related account; and whether any agent acting on
Dorman's behalf safeguards users’ crypto assets.
            You may contact Cara Lubit at 202-551-5909 or Marc Thomas at 202-551-3452 if you
have questions regarding comments on the financial statements and related matters.  Please
contact Sonia Bednarowski at 202-551-3666 or J. Nolan McWilliams, Acting Legal Branch
Chief, at 202-551-3217 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Finance
cc:       Herbert F. Kozlov

United States securities and exchange commission logo
September 6, 2022
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 2 to
Draft Registration Statement on Form S-1
Submitted August 15, 2022
CIK No. 0001438472
Dear Mr. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amendment No. 2 to Draft Registration Statement on Form S-1
Risk Factors
Risks Related to Our Business
A significant portion of our operating revenues is generated by our transaction, page 20
1.Please revise to disclose how the respective percentage amounts were determined,
explaining the reasons for fluctuations, for the periods presented.

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There are significant regulatory hurdles to launching new crypto-based products, page 39
2.You state on page 40 that the legal test for determining whether a particular crypto asset is
a security “evolves over time” and that the “SEC’s views in this area have evolved over
time and it is difficult to predict the direction or timing of any continuing evolution.”
These statements appear inappropriate given that the legal tests are well-established by
U.S. Supreme Court case law and the Commission and staff have issued reports, orders,
and statements that provide guidance on when a crypto asset may be a security for
purposes of the U.S. federal securities laws.  Please revise accordingly.
Management's Discussion and Analysis of Financial Condition and Results of Operations
Transaction and Clearing Fees, page 69
3.We note your disclosure that transaction fees represent fees you charge for the
performance obligation of executing a trade on your markets.  This appears to suggest that
you execute trades and that execution is your performance obligation.  Your disclosure on
page F-14 says that transaction and clearing fees involve a customer’s right to be matched
with a corresponding buyer and seller and to have the transaction executed, which appears
to suggest multiple obligations.  Please clarify your disclosures here and on page F-14 to
separately and clearly describe your specific performance obligations for transaction fees
and for clearing fees, ensuring consistency and granularity regarding your obligations.
Comparison of the Six Months Ended June 30, 2022 and 2021
Transaction and Clearing Fees, page 78
4.We note your disclosure that the table on page 78 presents transaction and clearing fees by
operating segment for the three and six months ended June 30, 2022 and 2021.  The table
appears to show only the six months ended June 30, 2022 and 2021.  Please revise.
Business
International Listings, page 117
5.We note your removal, here and elsewhere, of disclosures regarding the Hashdex Nasdaq
Crypto Index ETF.  We also note that your response to comment 14 indicates this product
has not traded to date on BSX.  Please address the items below.
•Your prior disclosures and responses appeared to indicate that the only crypto-related
product currently listed on BSX is the Hashdex Nasdaq Crypto Index ETF.  However,
the BSX website’s “listed issuers” page appears to show additional Hashdex products
that may be crypto-related, such as Hashdex Nasdaq Bitcoin ETF, Hashdex Nasdaq
Ethereum ETF, and Hashdex Crypto Metaverse ETF.  Please clarify for us what
crypto-related products are currently listed on BSX and which of them have traded to
date;
•Specify for us what types of revenue are or could be generated for you from these
products;
•Explain to us your specific role and obligations with respect to these types of

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products, including any obligation in the event that future related trades fail to settle
or deliver, and whether this differs as compared to your role and obligations for non-
crypto-related listings;
•Acknowledging your revisions on page 139 regarding MGEX clearing, clarify for us
whether BSX or any of your entities other than MGEX obtains control over crypto
assets, transacts in or executes crypto asset transactions, or accepts crypto assets as
collateral or other forms of payment; and
•Tell us what types of financial risk or loss you could incur related to these products,
and whether this differs in any way from products that are not crypto-related.
Our Proprietary Products, page 117
6.We note your disclosure on page 29 stating that your current portfolio of proprietary
products "includes the SPIKES Volatility products as well as the traditional MGEX
exclusively listed Hard Red Spring Wheat product."  We also note that the only
proprietary products discussed on pages 4 and 117 are SPIKES Volatility products.
Please revise, here and elsewhere in the document where appropriate, to (i) define
"proprietary product" and (ii) explain the differences, if any, between proprietary products
and exclusively listed products, including whether your role, responsibilities, or revenue
streams derived from products in each category differ.
7.Refer to your response to comment 3.  We note the removal of all references to your
BRIXX products, because they are being delisted, and to your tax rate products because
they have not traded to date.  Please address the items below.
•Clarify for us whether these are the only proprietary products not discussed in the
filing; and
•Given that your prior disclosures indicated you have added tax rate products as
recently as the fourth quarter of 2021, and these products still appear to be available,
explain to us why you believe removal of all references to them is more meaningful
to investors than including such disclosure and noting that they have not traded to
date.
8.Refer to your response to comment 15.  Please explain here why you are delisting the
BRIXX Commercial Real Estate Products and what your plans are regarding the SIL
Products, which you state are listed but have not traded to date.
Expanding our proprietary products, page 121
9.We note your disclosure that you plan to launch products including futures and options on
cryptocurrency.  Please tell us your expected roles and responsibilities with regards to
such products, including whether you expect any crypto assets to move through your
systems, whether you would own or have control over crypto assets at any time, and
whether the settlement and delivery process would differ for these products as compared
to those unrelated to cryptocurrencies.

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Our Growth Strategy
Expanding into emerging, regulated cryptocurrency and digital asset markets, page 121
10.Refer to your response to comment 14.  You state that that you intend to offer crypto asset
products in Bermuda on BSX prior to introducing those products in the United States.
Please disclose here the processes and procedures you intend to use to prevent offers and
sales of those products to U.S. persons or persons located in the U.S.
Our Technology, page 125
11.Refer to your response to comment 17.  Please describe the basis for your belief that your
system operates at a speed that far exceeds your peers and provide quantitative context for
this assertion and clarify what you mean by "legacy" technology.
CFTC Regulation, page 138
12.We note your response to comment 2 and revised disclosures on page 139.  Please address
the items below.
•Tell us whether you have incurred any loss associated with clearing Bitnomial
products and, if so, quantify such losses for the periods presented in the filing;
•Quantify for us your maximum potential loss or exposure amounts related to
Bitnomial products during the periods presented, on a gross basis and after
consideration of mitigating collateral and Bitnomial default pool assets; and
•With regards to your disclosures, please revise to (i) address your obligations in the
event that Bitnomial were to file for bankruptcy or if a party failed to post sufficient
collateral prior to delivery and (ii) provide, here or elsewhere, such as in MD&A,
quantitative detail specific to Bitnomial transactions (e.g., volumes for the periods
presented), to give a sense of size and trending.
Underwriting, page 196
13.Refer to your response to comment 19.  Please revise the first full sentence on page 198 to
remove the implication that Regulation M distribution would potentially continue and the
applicable restricted period may not have ended.
Notes to Consolidated Financial Statements
4. Revenue Recognition, page F-14
14.Please enhance your disclosure to explain more fully what “enabling transaction-based
trading” means.
15.Please expand your revenue recognition disclosures to ensure that they address the items
below for each of your revenue streams.
•Explicitly state whether member firms or any other parties are your customers, as
defined by ASC 606;
•Clearly identify and discuss the promised goods or services as well as your specific

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performance obligation(s) and to whom it is (they are) provided;
•Disclose the consideration specified in the contract, whether it is fixed or variable,
and, if variable, discuss any constraints; and
•Note the transaction price as defined by ASC 606.
In addition, ensure that any related disclosures throughout the document consistently
characterize each of these points.
16.In conjunction with the comment above, please revise your disclosures regarding
transaction and clearing services revenue recognition to separately define transaction
services and clearing services and to address each individually when relevant
considerations, such as performance obligations, may differ.  For example, if a product is
listed on your exchange, but you do not clear it, it would seem that performance
obligations may differ from products that you clear.  Additionally, your disclosures should
address any differences in performance obligations as it relates to crypto-related products,
for which the clearing process appears to differ slightly.
17.Please clarify your disclosures to indicate where initial and annual listing fees flow for
each of your exchanges, as applicable.
Notes to Condensed Consolidated Financial Statements (unaudited)
2. Summary of Significant Accounting Policies
Recent Accounting Pronouncements, page F-46
18.We note your disclosure that you recognized a cumulative-effect adjustment to beginning
accumulated earnings / deficit as of the adoption date (January 1, 2022) for ASC 842.
However, we do not see an adjustment line item for Accumulated Deficit in the
Condensed Consolidated Statements of Changes in Stockholders’ Equity on page F-43.
Please revise to quantify this adjustment.
4. Investments, page F-50
19.We note your disclosure that you recorded a $2.5 million loss related to an other-than-
temporary impairment of one of your investments.  Please revise your disclosures to
explain what drove this impairment charge.
15. Equity
Preferred Stock, page F-60
20.Please revise to disclose the fair value per share of the Series B preferred stock issued
during the periods presented.

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            You may contact Cara Lubit at 202-551-5909 or Marc Thomas at 202-551-3452 if you
have questions regarding comments on the financial statements and related matters.  Please
contact Sonia Bednarowski at 202-551-3666 or J. Nolan McWilliams, Acting Legal Branch
Chief, at 202-551-3217 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Finance
cc:       Herbert F. Kozlov

United States securities and exchange commission logo
July 25, 2022
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Amendment No. 1 to
Draft Registration Statement on Form S-1
Submitted July 5, 2022
CIK No. 0001438472
Dear Mr. Gallagher:
            We have reviewed your amended draft registration statement and have the following
comments.  In some of our comments, we may ask you to provide us with information so we
may better understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Amendment No. 1 to Draft Registration Statement on Form S-1
General
1.Refer to your response to comment 5.  Please disclose your process for determining
whether or not the crypto asset services or products you plan to offer in the U.S. or to U.S.
persons are securities under the federal securities laws and to ensure that you are not
facilitating, or engaging in, transactions of unregistered securities.  In your response,
describe your internal policies and procedures that allow you to reach the conclusion that
your products are not securities.  Please address in the last paragraph of the carryover risk
factor on pages 37-38 the risks and limitations of internal policies and procedures,
including that they are risk-based judgments made by you and not a legal standard or

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determination binding on any regulatory body or court.  Please also describe the
consequences if it is subsequently determined that a particular product or services is a
security.
2.Refer to your response to comment 4 and your disclosure that you do not custody crypto
assets.  Please address the items below.
•Explain in more detail your clearing activities and role for crypto-based products
such as those of Bitnomial, including but not limited to a discussion of whether and
how you facilitate delivery and whether and how your clearing services for these
products differ as compared to clearing for non-crypto-related products, if at all.
Also, clarify whether you clear all Bitnomial transactions for these products or only
those for which an involved entity is an MGEX and / or Bitnomial member.
•Understanding that you do not custody crypto assets, clarify for us whether you have
control over any crypto assets at any time in performing your duties and how you
reached your conclusion.
•Tell us whether any of your entities have access to the private keys of crypto assets at
any time and whether crypto assets are transferred through your systems.
•Clarify whether you accept crypto assets as non-cash collateral in any instance and
whether you take possession of such assets (such as for liquidation purposes) in the
event that a Clearing Member fails to perform its clearing obligations.
•Explain how you consider and quantify risks associated with clearing crypto-based
products.
Prospectus Summary
Tax Rate Products, page 5
3.Refer to your response to comment 11 and tax rate product disclosures (e.g., page 102).
Please quantify for us the trading volume and revenues contributed by SIG Index
Licensing, LLC products (tax rate products) for applicable 2021 and 2022 quarterly
periods.
Our Competitive Strengths
Multi-Asset Exchange Operator with Broad Portfolio Licenses, page 6
4.Refer to your response to comment 12.  Please identify each cryptocurrency and digital
asset product and service you offer that is regulated under either your DCO license
or DCM license and clarify that none of these products are regulated under national
securities exchange licenses.
Successful History of M&A Strategic Investments, page 6
5.Refer to your response to comment 10.  Please place the disclosure on page 5 in context
by summarizing the material aspects of the strategic investments with T3, Lukka, MEEG,
MidChains, Vesica, Statifi, Diamond Standard, and Options AI.

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Our Growth Strategies, page 7
6.Refer to your response to comment 1.  Please clarify that you have no current plans to
offer futures contracts on any other crypto assets other than those discussed on pages 8
and 105.
Risk Factors, page 19
7.Refer to your response to comment 24.  Please add a risk factor addressing the inverted
pricing you have been experiencing in your Equities segment and the waiver of fees for
certain new products in your Future segment.
Financial or other problems experienced by third parties, page 25
8.Refer to the first paragraph on page 26.  Given the various categories of products you and
your affiliates trade or hold, please discuss volatility in markets in addition to securities
markets, such as commodities and cryptocurrencies markets, as well as related futures and
options on these products.  Discuss here all types of risk exposure (e.g. market, credit,
interest rate, etc.)  you are exposed to from the specific market actors, broker-dealers,
DCOs, exchanges, clearing organizations, and counterparties.  Include a cross-reference to
expanded discussions relating to these types of entities and risks elsewhere in the
prospectus.
Risks Related to Owning a Clearing House, page 26
9.Refer to your response to comment 15.  Please specifically address the risks to you as the
"exclusive venue" for clearing crypto asset products.  To the extent these risks are
mitigated because you do not take custody of any crypto assets, so state.
Our ability to implement or amend rules, page 37
10.You state here and in the next risk factor that "any crypto asset product traded or cleared
must first be deemed a commodity under the Commodity Exchange Act, rather than a
security under the federal securities laws."  Please clarify who deems the crypto asset
product a commodity: you or your affiliates, or a regulator such as the CFTC or SEC as
part of applications and rule filings to trade the crypto asset product.  Also summarize the
determination process and considerations here and describe in greater detail on pages 100
and 122-23.
Changes in the legislative or regulatory environment, page 38
11.Refer to your response to comment 38.  Please briefly explain here and on page 94
payment for order flow and its importance to you.  Describe the legislative and regulatory
proposals and the extent to which proposals that would restrict or prohibit payment for
order flow arrangements may impact your transaction rebate model and business and
financial condition, and the impact of these risks to investors.

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Page 4
Management's Discussion and Analysis of financial Condition and Results of Operations
Key Factors Driving Our Performance, page 64
12.Refer to your response to comment 25.  Please discuss here how you use ADV, trading
days and RPC metrics to manage the business and describe any limitations in using these
metrics given the lack of comparable information for the metrics in the table on page 73.
Please also discuss the reasons for period over period changes in the metrics in the table
on page 72.
Industry Overview
U.S. Futures Market, page 92
13.Refer to your response to comment 36.  Please disclose your market share for exchange-
traded futures.
International Listings, page 100
14.Refer to your response to comment 2.  Please describe the processes and procedures that
prevent offers and sales to U.S. persons or persons located in the U.S.  In this regard, it is
not clear how limiting offers and sales to “qualified investors” would prevent offers and
sales to U.S. persons or persons located in the U.S.
Our Proprietary Products, page 102
15.Refer to your response to comment 41.  Please briefly describe your role and
responsibilities in your collaborative effort with Advanced Fundamentals and with SIL.
Our Strategic Investments, page 106
16.Refer to your response to comment 3.  Please describe the products you may list with
MidChains and whether you intend to offer any of these to U.S. investors.
Our Technology, page 108
17.Refer to your response to comment 47.  Please substantiate your statements that
throughput is "exceptional," latency access is "ultra-low" and wire determinism is "best-
in-class" and provide quantitative and qualitative context for these assertions.
Human Capital
Diversity, page 114
18.Refer to your response to comment 49.  Please briefly describe how the ESG Steering
Committee measures and evaluates your progress on short-term and long-term ESG and
diversity goals.

 FirstName LastNameThomas P. Gallagher
 Comapany NameMiami International Holdings, Inc.
 July 25, 2022 Page 5
 FirstName LastName
Thomas P. Gallagher
Miami International Holdings, Inc.
July 25, 2022
Page 5
Underwriting, page 178
19.You state on page 180 that "[a]s an additional means of facilitating this offering, the
underwriters may bid for, and purchase, shares of common stock in the open market to
stabilize the price of the common stock."  Please clarify what you mean by "open market"
given this is your initial public offering and a market for your securities has not yet been
established.  To the extent that you are referring to the aftermarket, please provide your
analysis for how such stabilizing may be engaged in without extending or continuing the
initial "distribution" (and, thus, the "restricted period") for purposes of Regulation M.
20.Refer to the two paragraphs preceding the Pricing of the Offering section on page 180.
Please disclose that this activity would only be engaged in to the extent the underwiters
and their respective affiliates are able to so in accordance with the limitations and
restrictions in Rules 101 and 102 of Regulation M.
            You may contact Cara Lubit at 202-551-5909 or Marc Thomas at 202-551-3452 if you
have questions regarding comments on the financial statements and related matters. Please
contact Sonia Bednarowski at 202-551-3666 or J. Nolan McWilliams, Acting Legal Branch
Chief, at 202-551-3217 with any other questions.
Sincerely,
Division of Corporation Finance
Office of Finance
cc:       Herbert F. Kozlov

United States securities and exchange commission logo
May 27, 2022
Thomas P. Gallagher
Chief Executive Officer
Miami International Holdings, Inc.
7 Roszel Road, Suite 1A
Princeton, NJ 08540
Re:Miami International Holdings, Inc.
Draft Registration Statement on Form S-1
Submitted April 26, 2022
CIK No. 0001438472
Dear Mr. Gallagher:
            We have reviewed your draft registration statement and have the following comments.  In
some of our comments, we may ask you to provide us with information so we may better
understand your disclosure.
            Please respond to this letter by providing the requested information and either submitting
an amended draft registration statement or publicly filing your registration statement on
EDGAR.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
            After reviewing the information you provide in response to these comments and your
amended draft registration statement or filed registration statement, we may have additional
comments.
Draft Registration Statement on Form S-1
General
1.Please describe the regulatory approvals needed to launch CFTC-regulated futures
contracts based on crypto assets.  Discuss your intentions to launch products based on
Bitcoin and Ether.  Discuss whether you plan to offer futures contracts on other crypto
assets and, if so, which ones and how you will determine that those crypto assets are not
securities within the meaning of the U.S. federal securities laws.  Revise your risk factors
as necessary to describe the attendant risks.
2.Please discuss in greater detail your BSX-listed and -quoted crypto asset products
including whether these products will be available in the U.S. or to U.S. persons.  To the
extent these products will be available in the U.S. or to U.S. persons, tell us how you will

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do so without facilitating unregistered transactions in securities.  Revise your risk factors
as necessary to describe the attendant risks.
3.You state that the MidChains institutional cryptocurrency and digital asset trading
exchange will serve as an important component of your cryptocurrency and digital asset
strategy.  Please disclose what crypto assets trade on this platform and discuss what
products you expect will be offered from the planned commercial agreement.  Disclose
whether the MidChains platform is available in the U.S. or to U.S. persons.  To the extent
the platform is available in the U.S. or to U.S. persons, tell us how you ensure this is
conducted without facilitating unregistered transactions in securities.  Similarly, disclose
whether products that may be launched from the planned commercial agreement will be
available in the U.S. or to U.S. persons.  If so, tell us how to will do so without facilitating
unregistered transactions in securities.  Revise your risk factors as necessary to describe
the attendant risks.
4.Please clarify for us whether you provide a service to safeguard any user or customer
crypto assets and whether you or an agent acting on your behalf is therefore obligated to
secure these assets and protect them from loss, theft, or other misuse.  Relatedly, tell us
how you concluded whether recently issued Staff Accounting Bulletin No. 121 applies to
you and, to the extent that it does apply, provide a detailed analysis of how you considered
this SAB, including how you considered the regulatory, technological, and legal risks and
loss exposure associated with safeguarding crypto assets for your users or customers.
Prospectus Summary, page 1
5.Please revise the Summary and throughout to balance your disclosure regarding your
crypto asset activities by addressing the significant regulatory hurdles to launching new
crypto asset products, including determining whether those products implicate the federal
securities laws.  Your revised disclosure should acknowledge these regulatory hurdles
notwithstanding your licenses and approvals.
U.S. Options, page 2
6.Please briefly explain the customer rebate pricing structure and the maker-taker fee
structure and how these differ from other fee structures you discuss in the Business
section.
U.S. Futures, page 3
7.On page 3, you disclose that the MGEX's unrestricted DCM and DCO licenses are highly
valuable given the limited number of current licensees.  Please quantify the number of
licenses and balance your disclosure by discussing the competitive market for execution
services and clearing services.  We note your disclosure on pages 101 and 102.

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Miami International Holdings, Inc.
May 27, 2022
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Our Competitive Strengths, page 4
8.You state that your trading system has "best-in-class" speed, performance and risk
protections.  Please briefly describe here the speed, performance and risk protections of
your technology platform and describe these in greater detail in your Business section.
Please also substantiate that the system is "best-in-class."
9.We note your disclosure that your leadership team has "over two decades of experience in
developing, operating, and trading on exchanges."  Please disclose the average number of
years of your leadership team's experience in developing, operating, and trading on
exchanges as well as the range of years.
10.Please summarize the "successful strategic investments" with T3, Lukka, MEEG,
MidChains, Vesica, Stratifi, Diamond Standard, and OptionsAI you reference on page 5,
and describe the material terms of any stockholder or other agreements with these entities.
Tax Rate Products, page 4
11.Please describe, here or elsewhere as appropriate, the material terms of your collaboration
with SIG Index Licensing, LLC.
Multi-Asset Exchange Operator, page 5
12.Please describe which cryptocurrency and digital assets products are regulated through
your DCO and DCM licenses with the CFTC and which are regulated through national
securities licenses and briefly explain how these products are regulated.  Similarly revise
the second full paragraph on page 7 to explain how your national securities, DCM, and
DCO licenses can be “leveraged” for the development of new products.
Our Growth Strategy, page 6
13.In addition to the cryptocurrency products that clear through MGEX, please tell us what
other crypto asset related products currently trade on each of your markets.  In addition,
tell us whether you execute any crypto-related trades or take control or ownership of
crypto assets at any time and, if so, in what context.
14.Please disclose here an estimated timeframe for the each one of the planned products
discussed in this section, the estimated funds needed to accomplish your growth strategy
and the sources of those funds, and summarize the challenges you may face in
implementing your growth strategy.   If this information has not yet been determined,
discuss the factors that you will consider in determining whether and when to develop a
particular product.  Similarly revise your risk factors to describe the attendant risks.
Expanding into the emerging, regulated cryptocurrency and digital asset markets, page 7
15.You state that MGEX serves as the exclusive venue for the clearing of certain
cryptocurrency products listed for trading on the Bitnomial Exchange.  Please briefly

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describe here and in greater detail in your Business section the cryptocurrency products
you clear, including whether these are cash-settled or physically delivered contracts,
whether you accept crypto assets, and, if so, the types of crypto assets accepted.

If you accept crypto assets, disclose in your Business section (i) whether you use a third
party to custody the crypto assets, (ii) whether these are held in cold wallets, (iii) the
geographic location where the crypto assets are held in cold wallets, if applicable, (iv) the
procedures for holding crypto assets, (v) whether any persons (e.g., auditors, etc.) are
responsible for verifying the existence of the crypto assets if held by a third-party
custodian, and, (vi) to the extent that you use a third-party custodian, whether the
custodian has insurance for the loss or theft of the crypto assets.  Also add risk factor
disclosure specifically addressing the material risks of clearing crypto asset products.
16.Refer to the last sentence in this subsection.  Please briefly describe how the Bermuda
regulatory environment provides “high international regulatory standards” and reconcile
the statement about “legal and regulatory certainty” with the carryover risk factor on
pages 35-36.
Post-Offering Balance Sheet, page 8
17.We note your disclosure that the $302.8 million liability associated with outstanding
warrants on puttable shares and puttable common stock will be extinguished upon closing
of the offering.  Please revise to clarify how and why this liability will be extinguished.
Implications of Being an Emerging Growth Company, page 10
18.Please provide us with copies of all written communications, as defined in Rule 405 under
the Securities Act, that you, or anyone authorized to do so on your behalf, present
to potential investors in reliance on Section 5(d) of the Securities Act, whether or not they
retain copies of the communications.  Please contact Sonia Bednarowski at the number
below to discuss how to submit the materials, if any, to us for our review.
Global economic, political and financial market events, page 18
19.Please describe in a separate risk factor how specific policies related to Russia's invasion
of Ukraine or economic or other consequences have impacted and are expected to impact
your business and future opportunities, including how your business is impacted by price
volatility in wheat and other commodities markets and supply chain disruptions.
Risk Factors, page 18
20.Please add a risk factor describing the risks from the competitive environment for your
prospective crypto asset products and activities.  We note that there are already DCMs
trading Bitcoin and Ether futures contracts and other significant competition in this
market.

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 May 27, 2022 Page 5
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Miami International Holdings, Inc.
May 27, 2022
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Risks Related to Our Business
Our failure to maintain order flow, page 19
21.Please clarify what you mean by your disclosure that you have one "active" equity rights
program (ERP).  In addition, disclose here the number of vested and unvested warrants
outstanding pursuant to your ERPs, the number of additional warrants you may issue
under the programs, the terms of the warrants, including the exercise prices, as well a
description of the underlying securities, including the associated put rights in connection
with ERP I and II.  Revise the Prospectus Summary and Description of Capital Stock
sections to disclose that the unvested warrants awarded under ERP V will become vested
in connection with the completion of this offering.
Revenues from our market data fees and access fees, page 20
22.Please disclose here the percentage of your revenue earned both from your market
data products and from the non-transaction fees on your exchanges.
Regulatory action adversely affecting proprietary products, page 34
23.Please place the risks related to the challenge to the SEC Order in context by describing
other regulatory approvals you may seek if the Order is overturned and the potential
impact on the operation of the SPIKES Futures market if you are unable to maintain or
receive approval.
Management's Discussion and Analysis
Key Factors Driving Our Performance, page 61
24.Please discuss, including quantitatively where possible, any known trends or uncertainties
that have had, or that you reasonably expect will have, a material favorable or unfavorable
impact on revenue or results of operations.  We note by way of example your general
discussion of key drivers here, and your disclosure on page 75 regarding negative net
transaction fees resulting from “inverted pricing.”
25.Please tie the table of key business metrics on page 68 to your discussion of the key
factors driving your performance and results of operations.  In this regard, discuss how
average daily volume (ADV), trading days, and revenue per contract (RPC) metrics are
used to manage the business.
Key Components of Our Results of Operations
Transaction Rebates, page 63
26.Please discuss in greater detail the reasons why transaction rebates exceed transaction
fees, including for new proprietary products.  Also discuss “inverted pricing,” how trading
volume and transaction rebates and fees influence order routing, and the extent to which
transaction rebates are used to direct order flow.

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 May 27, 2022 Page 6
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Equity Rights Program, page 63
27.We note the disclosures that three customers accounted for significant levels of revenues
in both fiscal periods 2020 and 2021. Please revise to disclose if these customers
participated in any of your ERPs and, if so, quantify their respective participation amounts
in each of the ERP issuances. Further, given the importance of these customers and the
risk factor disclosure on page 8 that your “failure to maintain order flow from providers
following the expiration of [your] ERPs could negatively affect [your] results of
operations," please disclose the nature and terms of the contractual arrangements with
these customers. Your disclosures should also indicate if the costs incurred in these
relationships have exceeded revenues generated during each fiscal period of the
relationship.
28.We note your disclosure that the last share-based payment related to ERP is set to be made
upon the earlier of June 30, 2023 or upon an accelerated vesting at the time of an initial
public offering of the Company, including this offering. Please revise to address the points
below.
•Explain what specifically becomes eligible for vesting at the time of an initial public
offering, what happens to these vested instruments, and the accounting treatment
being followed for these items, including references to the individual ERPs.
•Clarify what remains unvested at the time of an initial public offering and how this
will be reflected in your financial statements.
•Quantify what aggregate payments, and in what form, could be required for all
instruments that are vested and unvested at the time of the initial public offering.
•Address whether you will make any related payments from the issuance proceeds
and, if not, the sources of liquidity to be used.
Comparison of Years Ended December 31, 2021 and 2020
Overview, page 65
29.We note your narrative footnote on page 66 describing the calculation of adjusted
revenues less cost of revenues.  Please revise your disclosures to include a reconciliation
to the most directly comparable financial measure calculated and presented in accordance
with U.S. GAAP.
Key Business Metrics, page 68
30.Please revise to address the total contracts traded during the period as well the reasons for
the decrease in total options revenue per contract in fiscal 2021 compared to fiscal 2020.
31.Please clarify your disclosures to disclose the reasons that the (i) equities capture rate and
(ii) futures financial revenues per contract were negative for