SEC FORM 3 SEC Form 3
FORM 3 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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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1. Name and Address of Reporting Person*
Atlas Venture Fund IX, L.P.

(Last) (First) (Middle)
25 FIRST STREET, SUITE 303

(Street)
CAMBRIDGE MA 02141

(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
11/01/2017
3. Issuer Name and Ticker or Trading Symbol
Spero Therapeutics, Inc. [ SPRO ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director X 10% Owner
Officer (give title below) Other (specify below)
5. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
Form filed by One Reporting Person
X Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock 42,781(1) D(7)
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year) 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Junior Preferred Stock (2) (2) Common Stock 245,605(3) (2) D(7)
Series A Preferred Stock (4) (4) Common Stock 246,272(3) (4) D(7)
Series B Preferred Stock (5) (5) Common Stock 328,992(3) (5) D(7)
Series C Preferred Stock (6) (6) Common Stock 513,318(3) (6) D(7)
1. Name and Address of Reporting Person*
Atlas Venture Fund IX, L.P.

(Last) (First) (Middle)
25 FIRST STREET, SUITE 303

(Street)
CAMBRIDGE MA 02141

(City) (State) (Zip)
1. Name and Address of Reporting Person*
Atlas Venture Associates IX, L.P.

(Last) (First) (Middle)
25 FIRST STREET, SUITE 303

(Street)
CAMBRIDGE MA 02141

(City) (State) (Zip)
1. Name and Address of Reporting Person*
Atlas Venture Associates IX, LLC

(Last) (First) (Middle)
25 FIRST STREET, SUITE 303

(Street)
CAMBRIDGE MA 02141

(City) (State) (Zip)
Explanation of Responses:
1. The number of shares reported reflects a 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017.
2. The shares of Junior preferred stock are convertible into the number of shares of common stock shown in Column 3, calculated using the conversion ratio set forth in the Issuer's Amended and Restated Certificate of Incorporation, as amended, at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date.
3. Share numbers give effect to the 1-for-6.0774 reverse stock split of the Issuer's common stock effected on October 20, 2017.
4. The shares of Series A preferred stock are convertible into the number of shares of common stock shown in Column 3, calculated using the conversion ratio set forth in the Issuer's Amended and Restated Certificate of Incorporation, as amended, at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date.
5. The shares of Series B preferred stock are convertible into the number of shares of common stock shown in Column 3, calculated using the conversion ratio set forth in the Issuer's Amended and Restated Certificate of Incorporation, as amended, at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date.
6. The shares of Series C preferred stock are convertible into the number of shares of common stock shown in Column 3, calculated using the conversion ratio set forth in the Issuer's Amended and Restated Certificate of Incorporation, as amended, at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The shares have no expiration date.
7. The shares are held directly by Atlas Venture Fund IX, L.P. ("Atlas Venture Fund IX"). The general partner of Atlas Venture Fund IX is Atlas Venture Associates IX, L.P. ("AVA IX LP"). Atlas Venture Associates IX, LLC ("AVA IX LLC") is the general partner of AVA IX LP. Each of AVA IX LP and AVA IX LLC disclaims beneficial ownership of the shares held by Atlas Venture Fund IX, except to the extent of its pecuniary interest therein.
Remarks:
Atlas Venture Fund IX, LP, By: Atlas Venture Associates IX, LP, its general partner, By: Atlas Venture Associates IX, LLC, its general partner, By: Frank Castellucci, General Counsel , /s/ Frank Castellucci 11/01/2017
Atlas Venture Associates IX, LP., By: Atlas Venture Associates IX, LLC, its general partner, By: Frank Castellucci, General Counsel, /s/ Frank Castellucci 11/01/2017
Atlas Venture Associates IX, LLC, By: Frank Castellucci, General Counsel, /s/ Frank Castellucci 11/01/2017
** Signature of Reporting Person Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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