SEC Form 4
FORM 4 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
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 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
1. Name and Address of Reporting Person*
Barrett Peter
(Last) (First) (Middle)
C/O ATLAS VENTURE
890 WINTER STREET, SUITE 320
(Street)
WALTHAM MA 02451
(City) (State) (Zip)
2. Issuer Name and Ticker or Trading Symbol
HELICOS BIOSCIENCES CORP [ HLCS ] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director X 10% Owner
Officer (give title below) Other (specify below)
3. Date of Earliest Transaction (Month/Day/Year)
05/30/2007
4. If Amendment, Date of 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
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 05/30/2007 C 2,654,433 A (1) 2,654,433 I See footnote.(2)
Common Stock 05/30/2007 P 333,333(8) A $9 2,987,766 I See footnote.(7)
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 Securities Underlying Derivative Security (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: 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 A Redeemable Convertible Preferred Stock (1) 05/30/2007 C 5,232,778(3) (1) (1) Common Stock 1,162,835 $0 0 I See footnote.(5)
Series B Redeemable Convertible Preferred Stock (1) 05/30/2007 C 6,712,209(4) (1) (1) Common Stock 1,491,598 $0 0 I See footnote.(6)
Explanation of Responses:
1. The preferred stock automatically converted upon the closing of the issuer's initial public offering, on a 4.5-for-one basis.
2. Consists of 13,970 shares held by Atlas Venture Entrepreneurs' Fund V, L.P., 839,297 shares held by Atlas Venture Fund V, L.P., 208,506 shares held by Atlas Venture Parallel Fund V-A, C.V., 1,518,426 shares held by Atlas Venture Fund VI, L.P., 27,801 shares held by Atlas Venture Fund VI-GmbH & Co. KG and 46,433 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
3. Consists of 27,541 shares held by Atlas Venture Entrepreneurs' Fund V, L.P., 1,654,532 shares held by Atlas Venture Fund V, L.P., 411,038 shares held by Atlas Venture Parallel Fund V-A, C.V., 2,993,321 shares held by Atlas Venture Fund VI, L.P., 54,809 shares held by Atlas Venture Fund VI-GmbH & Co. KG and 91,537 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
4. Consists of 35,328 shares held by Atlas Venture Entrepreneurs' Fund V, L.P., 2,122,308 shares held by Atlas Venture Fund V, L.P., 527,248 shares held by Atlas Venture Parallel Fund V-A, C.V., 3,839,601 shares held by Atlas Venture Fund VI, L.P., 70,306 shares held by Atlas Venture Fund VI-GmbH & Co. KG and 117,418 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
5. Consists of 6,120 shares held by Atlas Venture Entrepreneurs' Fund V, L.P., 367,673 shares held by Atlas Venture Fund V, L.P., 91,340 shares held by Atlas Venture Parallel Fund V-A, C.V., 665,182 shares held by Atlas Venture Fund VI, L.P., 12,179 shares held by Atlas Venture Fund VI-GmbH & Co. KG and 20,341 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
6. Consists of 7,850 shares held by Atlas Venture Entrepreneurs' Fund V, L.P., 471,624 shares held by Atlas Venture Fund V, L.P., 117,166 shares held by Atlas Venture Parallel Fund V-A, C.V., 853,244 shares held by Atlas Venture Fund VI, L.P., 15,622 shares held by Atlas Venture Fund VI-GmbH & Co. KG and 26,092 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
7. Consists of 15,724 shares held by Atlas Venture Entrepreneurs' Fund V, L.P., 944,693 shares held by Atlas Venture Fund V, L.P., 234,689 shares held by Atlas Venture Parallel Fund V-A, C.V., 1,709,104 shares held by Atlas Venture Fund VI, L.P., 31,292 shares held by Atlas Venture Fund VI-GmbH & Co. KG and 52,264 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
8. Consists of 1,754 shares purchased by Atlas Venture Entrepreneurs' Fund V, L.P., 105,396 shares purchased by Atlas Venture Fund V, L.P., 26,183 shares held by Atlas Venture Parallel Fund V-A, C.V., 190,678 shares purchased by Atlas Venture Fund VI, L.P., 3,491 shares purchased by by Atlas Venture Fund VI-GmbH & Co. KG and 5,831 shares held by Atlas Venture Entrepreneurs' Fund VI, L.P. Dr. Barrett is a partner with Atlas Venture. Dr. Barrett disclaims beneficial ownership of the shares except to the extent of his pecuniary interest therein.
/s/ Jeanne Larkin Henry, attorney-in-fact 05/30/2007
** Signature of Reporting Person Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* 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).
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