SecProbe.io

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September 23, 2005

VIA EDGAR TRANSMISSION AND FACSIMILE

Securities and Exchange Commission
Division of Corporate Finance
100 F Street, NE
Washington, D.C. 20549

Attn: Mr. Todd K. Schiffman, Esq.

RE:      PENSON WORLDWIDE, INC. REGISTRATION STATEMENT ON FORM S-1
         FILED AUGUST 10, 2005
         FILE NO. 333-127385

Dear Mr. Schiffman:

         We are writing on behalf of Penson Worldwide, Inc. (the "Company"), in
response to the letter of comments from the Staff of the Securities and Exchange
Commission to the Company dated September 9, 2005 (the "Comment Letter"), with
respect to the Company's Registration Statement on Form S-1, File No. 333-127385
(the "Registration Statement"). We are filing Amendment No. 3 to the
Registration Statement ("Amendment No. 3") in response to your Comment Letter.
The numbered paragraphs below restate the numbered paragraphs in the Comment
Letter in italics, and the discussion set out below each such paragraph is the
Company's response to the Staff's comment.

General

1.       We will process your amendment with missing information (e.g., pricing
         on cover page, offering on page 7, aggregated option exercises on page
         73, underwriting on page 99, Item 13 on page II-1, etc.). Since this
         missing information triggers a number of disclosure matters, we will
         need sufficient time to process the amendment when it is included.
         Please understand that its effect on disclosure throughout the document
         may cause us to raise issues in areas not previously commented on.

         The Company notes the Staff's comment.

2.       Please revise your disclosure to provide a brief description of
         industry terms such as algorithmic trading and Level II market
         information, or refer the reader to the location where you define such
         terms.

         In response to the Staff's comment, the Company has included a brief
         statement on page 1 of Amendment No. 3 referring the reader to the
         "Glossary of selected terms" where certain industry terms related to
         the Company's business are

                                       1.
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         discussed. The Company has also included additional terms in the
         "Glossary of selected terms."

3.       Please revise your disclosure to address your code of ethics. Refer to
         Item 406 of Regulation S-K.

         The Company advises the Staff that it adopted a code of ethics on July
         26, 2005, and has added a reference on page 74 to its code of ethics.

Market opportunity, page 3

4.       Please balance the discussion with a reference to the recent problems
         you have experienced in the UK market.

         In response to the Staff's comment, on page 4 the Company has revised
         its discussion of the opportunities in the Canadian and European
         markets to reference the recent difficulties it has experienced in
         implementing its operational plan in the U.K. In addition, the Company
         has expanded its discussions of the challenges it has faced in the U.K.
         market beginning on page 15 of the "Risk Factors" section.

Recent Developments, page 5

5.       Please revise to describe, or refer the reader to where in the
         prospectus that you discuss, the terms (including price, possible
         impact on financial performance and relevant risks and benefits) of
         your acquisition of CCS, Nexa Technologies and other entities. For
         example, the Stock Purchase Agreement by and among SAI Holdings, Inc.,
         Computer Clearing Services, Inc., and the Selling Stockholders includes
         the Closing Date Payment, defined as Book Value plus one million
         dollars; however, it is unclear how much the Book Value is worth.

         The Company has added a cross reference on page 6 to refer the reader
         to its risk factor on acquisitions and to its new discussion on
         acquisitions in the "Overview" section of the MD&A. The Company has
         also added a new disclosure on page 31 of the MD&A to discuss the terms
         of the CCS and Nexa acquisitions, as requested by the Staff.

Risk Factors
Risks related to our Business and industry
We depend on a limited number of clients for a significant portion of our...,
page 10

6.       Please revise to refer the investor to your discussion of the loss of
         your largest clearing correspondent in the United States (e.g., page
         33).

         The Company has referenced the discussion of the loss of the clearing
         correspondent on page 10 of Amendment No. 3.

                                       2.
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If we are unable to respond to demands of our existing and new. clients, our...,
page 14

7.       Several of your risk factors discuss generic issues. For example, this
         risk factor, the first two risk factors on page 15 and the middle risk
         factor on page 16, could apply to most companies. Please revise such
         risk factors to address risks that directly affect your company.

         In response to the Staff's comment, the Company has revised the risk
         factors referenced above which appear on pages 14-16 to describe how
         the risks directly affect the Company.

Risks related to this offering and our requirements as a public company
New investors will suffer immediate and substantial dilution in the tangible...,
page-21

8.       Please revise to refer the investor to the relevant sections regarding
         dilution, such as "Capitalization" and "Dilution" on, pages 25 and 26,
         respectively.

         In response to the Staff's comment, the Company has revised the risk
         factors on page 23 to refer to the relevant sections regarding
         dilution.

Management's discussion and analysis of financial condition and results of...,
page 29

9.       The discussion and analysis of known trends, demands, commitments,
         events and uncertainties help in an understanding a company's
         performance. Please revise to discuss trends, such as the decreasing
         revenues in dollar terms from 2000 to 2002, the fall in net revenues
         from clearing operations and the rise in interest income from 2002 to
         2004 discussed in the second paragraph on page 31, the quarterly rise
         in technology revenues and interest expense on page 40, or any other
         material known trends and uncertainties regarding your financial
         condition and the results of operations. Refer to III.B.3 of Release
         Number 33-8350 regarding MD&A, dated December 29, 2003.

         In response to the Staff's comment, the Company has revised its
         discussion and analysis of the material known trends, including the
         trends noted by the Staff, on page 30 of the MD&A.

10.      Please revise your discussion to more specifically address your
         negative cash flows from operations in 2004. More clearly disclose the
         reasons for this trend in operating cash flows. Disclose the steps you
         intend to take to address this trend, and identify the extent to which
         those steps have been implemented. Refer to Item 303(a)(1) of
         Regulation S-K.

         In response to the Staff's comment, the Company has added a statement
         in the "Overview" section of the MD&A to note the Company's continuing
         need for additional capital. The need is not as great as would be
         suggested by the Consolidated Statement of Cash Flows, as described
         below. The Company has also revised its discussion in the "Liquidity
         and capital resources" section of MD&A to address the unusual number
         for 2004 in its Consolidated Statement of

                                       3.
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         Cash Flows, and to explain that its growing business has had a need for
         additional cash since 2002. It is the Company's understanding that GAAP
         requires that statements of cash flows be prepared in a manner such
         that short term bank borrowings are shown in the "financing activities"
         section, while other sources of cash to fund customer requirements for
         liquidity, such as stock loans, are shown in the "operating activities"
         section. It is this GAAP requirement that has generated the unusual
         number in 2004 on the "net cash used in operating activities" line. The
         Company understands that this is a fairly common issue for financial
         sector companies. However, the existing GAAP requirements are not
         flexible in this regard. As noted in the Company's revised disclosure,
         the Company's actual need for additional capital is continuing but is
         much more modest than the 2004 number would suggest.

Overview, page 32

11.      You state on page 15 that you embarked upon an aggressive plan to roll
         out additional products and services in the U.K. in the fall of 2004
         and that the implementation of this roll-out was not successful. Either
         here or elsewhere as appropriate, provide a detailed discussion of the
         performance problems in the UK and the revisions to your operational
         plan and revise your MD&A to more clearly disclose this U.K. roll-out.
         Disclose the steps being taken to correct this roll-out implementation,
         and quantify the impact of this situation, both in terms of losses
         incurred and additional costs you expect to incur to correct it.

         In response to the Staff's comment, the Company has added a detailed
         discussion of the performance problems in the U.K. and the information
         requested by the Staff on pages 15, 16 and 34.

Quarterly Results of Operations, page 39

12.      Please revise to discuss the reasons for the rise in employee
         compensation benefits and the communications and data processing
         expenses for the quarters ended December 31, 2004, March 31, 2005 and
         June 30, 2005 given that these quarters immediately precede your
         proposed public offering.

         The Company has included a discussion of the reasons for the increase
         in the two expense categories on page 42 of Amendment No. 3.

Contractual obligations and commitments, page 41

13.      Your commitments and contingencies footnote on page F-18 indicates the
         existence of capital leases. Please revise the schedule of obligations
         and commitments on page 41 to include obligations under capital leases.
         Refer to Item 303(5)(B) of Regulation S-K.

         The Company has revised the schedule of obligations and commitments on
         page 44 to include obligations under capital leases.

                                       4.
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14.      Please revise your schedule to include obligations under repurchase
         agreements. Refer to Item 303 (5)(D) of Regulation S-K.

         The Company has noted on page 41 that there were no amounts outstanding
         under repurchase agreements at December 31, 2004. While the Company
         does enter into repurchase agreements from time to time, and therefore
         has an accounting policy relating to them, it did not have any
         outstanding repurchase agreements for the time period shown.

Qualitative and quantitative disclosure about market risk, page 43

15.      You discuss interest revenues and interest income in the section
         describing your business and include a risk factor titled, "[d]ecreases
         in short-term interest rates would negatively impact the profitability
         of our margin lending business." Please revise your disclosure in this
         section as it appears that you do have material exposure to interest
         rate changes. See Item 305 of Regulation S-K.

         The Company has revised the discussion of interest revenues and
         interest income under "Qualitative and quantitative disclosure about
         market risk" beginning on page 45 to discuss the impact of interest
         rate changes.

Industry
Types of clearing arrangements, page 50

16.      Please revise to describe how you fit into the industry (i.e., the
         United States has three types of clearing arrangements:
         fully-disclosed, omnibus clearing and facilities management programs.
         In which of these do you principally compete?).

         The Company has revised the discussion of types of clearing
         arrangements on page 54 to describe how it fits into the industry, and
         has provided a cross reference to its more detailed discussion of its
         clearing operations in the "Business" section.

Securities-processing, page 56

17.      Please revise to explain the SEC rules that govern your securities
         lending and borrowing.

         The Company has added the disclosure requested by Staff on page on
         pages 60 and 66 to describe the SEC rules governing securities lending
         and borrowing.

Management
Board Committees
Audit Committee, page 70

18.      Please revise to identify the expert on your audit committee and review
         Section 10A the Securities Exchange Act and its associated rules.
         Please advise how you plan to comply and refer also to Section 301 of
         the Sarbanes-Oxley Act of 2002.

                                       5.
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         The Company's Board of Directors intends to designate an "audit
         committee financial expert" prior to the effective date of its IPO and
         presently expects that it will designate Mr. David M. Kelly as such.
         Once the Board of Directors has made this determination, the Company
         will disclose the information in its Registration Statement. The
         Company is aware of the requirements of Section 10A of the Securities
         Exchange Act and its associated rules and Section 301 of the
         Sarbanes-Oxley Act of 2002. The Board of Directors is in the process of
         reviewing its membership and its compliance with those regulations and
         will be in compliance prior to the effectiveness of its IPO.

Compensation committee interlocks and insider participation, page 70

19.      Given the numerous relationships among directors, the company, its
         affiliates and outside parties discussed here as well as in "Other
         transactions" (promissory notes, personal guarantees, certain
         relationships and transactions, etc.) starting on page 80, consider
         including these as part of your disclosure on risk factors with
         emphasis on potential conflicts of interests.

         In response to the Staff's comment, the Company has added a reference
         in its risk factor on page 22 to reference the discussion under
         "Certain relationships and related transactions."

SAMCO Division and split off transaction, page 82

20.      You discuss the exchange of shares on page 83 as being a tax-free
         transaction, in addition to your disclosure on pages 29 and F-10
         concerning tax-free transactions. Please advise how you determined that
         there are no material tax consequences from your split-off.

         The Company has revised the language on pages 30, 31, 86 and 87 to
         clarify that the transactions were or are intended to be tax free.
         Although the structure was designed to be tax free, no tax opinion was
         obtained.

Description of capital stock, page 88

21.      Please revise your disclosure regarding the shares of preferred stock
         to include a detailed description of the rights, privileges, and
         conversion terms of this class of securities.

         The Company believes that it is not appropriate to include a detailed
         description