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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1. Name and Address of Reporting Person * SOBILOFF PETER   2. Issuer Name and Ticker or Trading Symbol Medidata Solutions, Inc. [MDSO] 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) 680 FITH AVENUE - 8TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 06/30/2009 (Street) NEW YORK, NY 10019 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 06/30/2009   C   5,436,706 A $ 0 (3) 5,440,277 (1) (2) I (2) See Footnote (2) (2) Common Stock 06/30/2009   S   631,835 D $ 13.02 (4) 4,808,442 (1) (2) I (2) See Footnote (2) (2) Common Stock 12/14/2009   S   2,960,528 D $ 14.175 (5) 1,847,914 (1) (2) I (2) See Footnote (2) (2) Common Stock 12/24/2009   S   825,000 D $ 14.175 (5) 1,022,914 (1) (2) I (2) See Footnote (2) (2)

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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

Series D Convertible Redeemable Preferred Stock

$ 0 (3)

06/30/2009

C

2,718,353

(3)

06/30/2009

common stock

5,436,706

$ 0

0

I (2)

See footnote (2) (2)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
SOBILOFF PETER 680 FITH AVENUE - 8TH FLOOR NEW YORK, NY 10019	X

Signatures

Peter Sobiloff		04/09/2010
**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 June 24, 2009, Peter Sobiloff was issued 3,571 shares of restricted stock ("Restricted Stock"). The shares of Restricted Stock vest over a two-year period, fifty percent (50%) on the first anniversary of the grant and the remaining fifty percent (50%) on the second anniversary of the grant. Peter Sobiloff is required to ultimately surrender or credit to Insight Venture Partners IV, L.P., Insight Venture Partners (Cayman) IV, L.P., Insight Venture Partners IV (Co-Investors), L.P. and Insight Venture Partners IV (Fund B), L.P. (collectively, the "Insight Partnerships") all compensation he receives from the Issuer, including all stock, stock options, restricted stock and other forms of stock-based awards, pro rata in accordance with such Insight Partnership's ownership of the Issuer's securities. Mr. Sobiloff therefore disclaims beneficial ownership of all such Restricted Stock and Options, except to the extent of his pecuniary interest therein.
(2)	The amount listed reflects the beneficial ownership of the Issuer's securities owned by the Insight Partnerships, all of which may be deemed attributable to the Insight Venture Associates IV, L.L.C. (the "Insight GP") because the Insight GP is the sole general partner of each of the Insight Partnerships. The managing member of the Insight GP is Insight Holdings Group, L.L.C. ("Insight Holdings"). Insight Holdings is managed by its board of managers. Jeffery Horing, Peter Sobiloff and Deven Parekh, the members of the board of managers of Insight Holdings, share the voting and investment power with respect to the securities held by the Insight Partnerships. Each of Messrs. Horing, Sobiloff and Parekh disclaim beneficial ownership of such securities, except to the extent of his pecuniary interest therein.
(3)	The Issuer's Series D Convertible Redeemable Preferred Stock automatically converted into Common Stock on a two-for-one basis immediately prior to the closing of the Issuer's initial public offering.
(4)	Represents public offering price of $14.00 per share less the underwriter's discount of $0.98 per share.
(5)	Represents public offering price of $15.00 per share less the underwriter's discount of $0.825 per share.

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