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 * Hsieh Ming   2. Issuer Name and Ticker or Trading Symbol Cogent, Inc. [COGT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Executive Officer (Last) (First) (Middle) 209 FAIR OAKS AVENUE 3. Date of Earliest Transaction (Month/Day/Year) 06/21/2005 (Street) SOUTH PASADENA, CA 91030 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 06/21/2005   M   600,000 A $ 0.3 601,215 (2) I See Footnote (1) Common Stock 06/21/2005   S   601,215 D $ 25.5 0 I See Footnote (1) Common Stock 06/21/2005   M   33,750 A $ 0.75 33,750 I See Footnote (1) Common Stock 06/21/2005   S   33,750 D $ 25.5 0 I See Footnote (1) Common Stock 06/21/2005   S   5,525,035 D $ 25.5 47,979,930 D   Common Stock 06/21/2005   S   220,000 D $ 25.5 2,780,000 I See Footnote (3) Common Stock 06/21/2005   S   220,000 D $ 25.5 2,780,000 I See Footnote (4) Common Stock 06/23/2005   S   1,650,000 D $ 25.5 46,329,930 D

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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

Employee Stock Option (right to buy)

$ 0.3

06/21/2005

M

600,000

(5)

08/18/2010

Common Stock

600,000

$ 0.3

0

I (1)

See Footnote

Employee Stock Option (right to buy)

$ 0.75

06/21/2005

M

33,750

(5)

01/01/2013

Common Stock

33,750

$ 0.75

26,250

I (1)

See Footnote

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Hsieh Ming 209 FAIR OAKS AVENUE SOUTH PASADENA, CA 91030	X	X	Chief Executive Officer

Signatures

Ming Hsieh		06/23/2005
**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)	By: Fang Liu Hsieh. The reporting person is the spouse of Fang Liu Hsieh. The reporting person disclaims beneficial ownership of these securities, and this report shall not be deemed an admission that the reporting person is the beneficial owner of the securities for purposes of Section 16 or for any other purpose.
(2)	Includes 1,215 shares acquired under the Cogent, Inc. 2004 Employee Stock Purchase Plan.
(3)	By: Ming Hsieh, as TTEE for the Ming Hsieh Annuity Trust No. 1 dated May 11, 2004.
(4)	By: Fang Liu Hsieh, as TTEE of the Fang Liu Hsieh Annuity Trust No. 1 dated May 12, 2004.
(5)	Options vest over a four year period based upon continued affiliation with Cogent, Inc.

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