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                                                                   EXHIBIT 10.21

                               SEVERANCE AGREEMENT

         AGREEMENT, dated and effective as of July 20, 2001 ("Agreement"),
between TRADESTATION GROUP, INC., a Florida corporation ("TSGroup"), and E.
STEVEN ZUM TOBEL ("Departing Person").

                              PRELIMINARY STATEMENT

         From December 29, 2000 through July 20, 2001, Departing Person has
served as an employee, officer and director of TSGroup and/or one or more of its
subsidiaries (the Company and its subsidiaries are hereinafter collectively
referred to as "Company") in the positions of: Vice President of Brokerage
Operations of TSGroup; director of TSGroup; President of TradeStation
Securities, Inc.; director of TradeStation Technologies, Inc.; and director of
TradeStation Securities, Inc. In connection with the termination of Departing
Person's employment with Company, Departing Person and Company have agreed to
create certain rights and obligations as set forth in this Agreement. The
purpose of this Agreement is to support an amicable termination of the
employment and agency relationships between the parties, for the mutual benefit
of all parties, and to settle any and all disputes the parties have concerning
to what payments Departing Person is entitled as a result of termination of such
employment and agency relationships.

         NOW, THEREFORE, in consideration of the foregoing, and the
consideration exchanged by the parties in, by and through this Agreement, the
receipt and sufficiency of which are conclusively acknowledged by each party,
the parties agree as follows:

         1. PRELIMINARY STATEMENT. Each party represents and warrants to the
other that the Preliminary Statement is correct and accurate.

         2. RESIGNATIONS. Departing Person hereby voluntarily resigns as a
director and as Vice President of Brokerage Operations of TSGroup, hereby
voluntarily resigns as a director and as President of its subsidiary,
TradeStation Securities, Inc., and hereby voluntarily resigns as a director of
TradeStation Technologies, Inc., and from any and all other employment and
agency relationships with Company. The Forms U5 filed in connection with such
resignations shall reflect that the resignations are voluntary, and Departing
Person shall, in connection with the foregoing resignations, execute, file
and/or deliver all such forms and documents as are required by applicable law or
regulations or otherwise appropriate or reasonably requested by Company. In
connection with such resignations, Departing Person shall promptly return to
Company all property and materials of Company of any kind and nature, tangible
or intangible, in Departing Person's possession or under his control.

         3. SEVERANCE PAY. In lieu of all payments, sums, amounts and other
compensation to which Departing Person may be entitled under Departing Person's
employment agreement with TSGroup or any other agreement or arrangement with
Company: (a) Company shall continue to pay Departing Person his base salary (at
the rate of $150,000 per annum) through December 29, 2002 (such payments shall
be made in the same manner and at the same times, and subject to the same
withholding procedures and practices, as the payments of his base salary prior
to his termination of employment); (b) TSGroup shall pay Departing Person the




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sum of $50,000 within three (3) business days of the date of this Agreement
(subject to normal withholding procedures and practices); (c) assuming Departing
Person exercises his COBRA rights, TradeStation Securities, Inc. shall pay the
basic premium, solely for Departing Person (and not for any dependents and not
for any additional or premium benefits) through December 2002; and (d) Departing
Person shall be entitled to keep his Company portable telephone and telephone
number through December 2001 (but shall pay all usage charges). The Company and
Departing Person shall make arrangements for Departing Person to receive on
CD-ROM copies of any personal files on Departing Person's Company personal
computer.

         4. RELEASE. Simultaneously with the execution and delivery of this
Agreement, Departing Person shall execute and deliver to Company the General
Release of All Claims, a copy of which is attached as Exhibit "A," and shall
comply with and observe all terms and conditions of such General Release of All
Claims, it being understood and agreed that the execution, delivery, performance
and observance by Departing Person of the General Release of All Claims is a
material inducement to TSGroup entering into this Agreement. TSGroup represents
and warrants to Departing Person that, based solely on the actual knowledge on
the date hereof of the executive management of TSGroup, there are no facts
relating to Departing Person's acts, omissions or conduct as an officer,
director or employee of Company that shall serve as the basis for any claim of
any kind by Company against Departing Person.

         5. CONFIDENTIALITY. Company and Departing Person agree that the
existence and terms of this Agreement are strictly confidential and neither
party shall disclose or disseminate any information concerning any term of this
Agreement except as necessary or appropriate to comply with applicable laws,
rules, regulations, court or administrative orders and the like, and except that
each party, as appropriate, may make disclosure to its or his legal or tax
advisors.

         6. GOVERNING LAW; VENUE. This Agreement shall be governed by and
construed and enforced in accordance with the laws of the State of Florida, both
substantive and remedial. Each of Company and Departing Person agrees that this
Agreement and any controversies of any nature whatsoever arising under or
relating to this Agreement shall be subject to the exclusive jurisdiction of the
courts of Miami-Dade County, Florida, and Miami-Dade County, Florida shall be
the exclusive jurisdiction and venue for any disputes, actions or lawsuits
arising out of or relating to this Agreement or the matters contemplated hereby.
The parties to this Agreement irrevocably waive, to the fullest extent permitted
by law, any objection which they may now or hereafter have to the laying of
venue of any suit, action or proceeding arising out of or relating to this
Agreement, or any judgment entered by any court in respect thereof, in
Miami-Dade County, Florida, and further irrevocably waive any claim that any
suit, action or proceeding brought in Miami-Dade County, Florida has been
brought in an inconvenient forum.

         7. ENTIRE AGREEMENT. This Agreement (together with the General Release
of All Claims) represents the entire understanding and agreement between the
parties hereto with respect to the subject matter hereof and there are no
promises, agreements, conditions, undertakings, warranties or representations,
whether written or oral, express or implied, between the parties other than as
set forth herein. Except as otherwise expressly set forth in this Agreement or
the General Release of All Claims, and except for the Indemnity Agreement




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between TSGroup and Departing Person and any indemnification rights that may
exist under TSGroup's bylaws or Florida law, this Agreement supersedes and
replaces any and all other agreements of any kind or nature between Departing
Person and TSGroup that relate in any way to the performance of, or failure to
perform, duties of Departing Person for Company and the parties' respective
rights and obligations with respect to matters that arise therefrom. This
Agreement cannot be amended, supplemented or modified except by an instrument in
writing signed by the parties against whom enforcement of such amendment,
supplement or modification is sought.

         IN WITNESS WHEREOF, the parties have executed and delivered this
Agreement as of the date first above written.

                             TRADESTATION GROUP, INC., a Florida corporation


                             By:      /s/ MARC J. STONE
                                -----------------------------------------
                                   Name:       MARC J. STONE
                                        ---------------------------------
                                   Title:      VICE PRESIDENT
                                         --------------------------------



                                 /s/ E. STEVEN ZUM TOBEL
                                -----------------------------------------
                                     E. STEVEN ZUM TOBEL





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