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*
MARXE AUSTIN W & GREENHOUSE DAVID M

(Last) (First) (Middle)
C/O SPECIAL SITUATIONS FUNDS
527 MADISON AVENUE, SUITE 2600

(Street)
NEW YORK NY 10022

(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
04/29/2011
3. Issuer Name and Ticker or Trading Symbol
POWER SOLUTIONS INTERNATIONAL, INC. [ FMRT ]
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)
X Form filed by One Reporting Person
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)
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
Convertible Preferred Stock (1) (1) Common Stock 2,343,526 (2) (3) 0.375 (3) I (2) By Limited Partnerships (2)
Explanation of Responses:
1. Each share of Series A Convertible Preferred Stock is initially convertible at any time at the election of the holder
2. This is a joint filing by Austin W. Marxe (Marxe) & David M. Greenhouse (Greenhouse). They share voting and investment control over all securities owned by Special Situations Fund III QP, L.P. (QP), Special Situations Cayman Fund, L.P. (Cay) and Special Situations Private Equity Fund, LP (PE), respectively. 4,900 PS cvrt into 1,640,468 shares of CS are held by QP, 1,400 P.S. cvrt into 468,705 shares of CS are held by Cay and 700 PS cvrt into 2,343,526 shares of CS are held by PE. The interest of Marxe and Greenhouse in the shares of Preferred Stock owned by QP, Cay & PE is limited to the extent of his pecuniary interest.
3. The shares of common stock issuable upon conversion of the Series A Convertible Preferred Stock are subject to the limitations, set forth in the Certificate of Designation.
Austin W. Marxe 05/10/2011
David M. Greenhouse 05/10/2011
** 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 5 (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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