Ownership Submission
FORM 4
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
Sheridan Scott Daniel
  2. Issuer Name and Ticker or Trading Symbol
THINKORSWIM GROUP INC. [SWIM]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)
600 WEST CHICAGO AVENUE, SUITE 100
3. Date of Earliest Transaction (Month/Day/Year)
02/15/2009
(Street)

CHICAGO, IL 60610
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)
7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 02/15/2009   J(1)   50,145 A $ 0 (1) 4,491,048 D  
Common Stock 02/15/2009   J(2)   285 A $ 0 (2) 25,142 I By Scott Sheridan Trust

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4, and 5)
6. Date Exercisable and Expiration Date
(Month/Day/Year)
7. Title and Amount of Underlying Securities
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 4)
10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)
11. Nature of Indirect Beneficial Ownership
(Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Sheridan Scott Daniel
600 WEST CHICAGO AVENUE
SUITE 100
CHICAGO, IL 60610
  X      

Signatures

 /s/ Scott Daniel Sheridan   02/17/2009
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) On 2/15/09, filer became entitled to receive 50,145 shares of the Issuer's common stock pursuant to the Agreement and Plan of Merger ("Agreement") among Investools Inc., thinkorswim Group, Inc. and Atomic Acquisition Corp. dated 9/18/06, under which the companies merged on 2/15/07. Under the Agreement certain former shareholders, including filer, were to receive additional shares of Issuer's stock, for no additional consideration, if the price of Issuer's stock was below a certain threshold as of 2/15/09. Since the trading price was below the threshold, the filer acquired additional shares as of 2/15/09, pursuant to a formula in the Agreement, which provides that for purposes of determining the shares issuable, the stock would be valued at a weighted average of the 20 trading days prior to 2/15/09, $8.10. The filer's right to receive additional shares became fixed and irrevocable on 2/15/07, the effective date of the merger.
(2) On 2/15/09 the Scott Sheridan Trust became entitled to receive additional 285 shares for no additional consideration under the Agreement pursuant to the right described in footnote 1.

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