UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. _ )* Active Power, Inc. (Name of Issuer) Common Stock (Title of Class of Securities) 00504W100 (CUSIP Number) December 31, 2007 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: [X] Rule 13d-1(b) [_] Rule 13d-1(c) [_] Rule 13d-1(d) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).
SCHEDULE 13G CUSIP No. 00504W100 - -------------------------------------------------------------------------------- 1. Names of Reporting Persons. I.R.S. Identification Nos. of above persons (entities only). Invesco Ltd. PowerShares Capital Management LLC - -------------------------------------------------------------------------------- 2. Check the Appropriate Box if a Member of a Group (see Instructions) (a) (b) - -------------------------------------------------------------------------------- 3. SEC Use Only _______________________________________________ - -------------------------------------------------------------------------------- 4. Citizenship or Place of Organization Invesco Ltd. - Bermuda PowerShares Capital Management LLC - US - -------------------------------------------------------------------------------- 5. Sole Voting Power 3,470,222: Such shares are held by the following entities in the respective amounts listed: PowerShares Capital Management LLC - 3,470,222 Number of Shares ---------------------------------------------------------- Beneficially Owned by Each Reporting 6. Shared Voting Power ______-0-______ Person With ---------------------------------------------------------- 7. Sole Dispositive Power 3,470,222: Such shares are held by the following entities in the respective amounts listed: PowerShares Capital Management LLC - 3,470,222 ---------------------------------------------------------- 8. Shared Dispositive Power ______-0-______ - -------------------------------------------------------------------------------- 9. Aggregate Amount Beneficially Owned by Each Reporting Person: 3,470,222 - -------------------------------------------------------------------------------- 10. Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) N/A - -------------------------------------------------------------------------------- 11. Percent of Class Represented by Amount in Row (9) 5.75% ---- - -------------------------------------------------------------------------------- 12. Type of Reporting Person (See Instructions) IA, HC. See Items 2 and 3 of this statement.
SCHEDULE 13G Item 1(a) Name of Issuer: Active Power, Inc. Item 1(b) Address of Issuer's Principal Executive Offices: 2128 West Braker Lane BK12 Austin, TX 78758 United States Item 2(a) Name of Person Filing: Invesco Ltd. In accordance with Securities and Exchange Commission Release No. 34-39538 (January 12, 1998), this statement on Schedule 13G or amendment thereto is being filed by Invesco Ltd. ("Invesco"), a Bermuda Company, on behalf of itself and its subsidiaries listed in Item 4 of the cover of this statement. Invesco through such subsidiaries provides investment management services to institutional and individual investors worldwide. Executive officers and directors of Invesco or its subsidiaries may beneficially own shares of the securities of the issuer to which this statement relates (the "Shares"), and such Shares are not reported in this statement. Invesco and its subsidiaries disclaim beneficial ownership of Shares beneficially owned by any of their executive officers and directors. Each of Invesco's direct and indirect subsidiaries also disclaim beneficial ownership of Shares beneficially owned by Invesco and any other subsidiary. Item 2(b) Address of Principal Business Office: 1360 Peachtree Street NE Atlanta, GA 30309 United States Item 2(c) Citizenship: See the response to Item 2(a) of this statement. Item 2(d) Title of Class of Securities: Common Stock, $.001 par value per share Item 2(e) CUSIP Number: 00504W100 Item 3 If this statement is filed pursuant to ss240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: (e) [x] An investment adviser in accordance with section 240.13d-1(b)(1)(ii)(E) (g) [x] A parent holding company or control person in accordance with section 240.13d-1(b)(1)(ii)(G) As noted in Item 2 above, Invesco is making this filing on behalf of its subsidiaries listed herein. Each of these entities is either an investment adviser registered with the United States Securities and Exchange Commission under Section 203 of the Investment Advisers Act of 1940, as amended, or under similar laws of other jurisdictions. Invesco is a holding company.
Item 4 Ownership: Please see responses to Items 5-8 on the cover of this statement, which are incorporated herein by reference. Item 5 Ownership of Five Percent or Less of a Class: If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [ ] Item 6 Ownership of More than Five Percent on Behalf of Another Person: N/A Item 7 Identification and Classification of the Subsidiary Which Acquired the Security Being reported on By the Parent Holding Company: Please see Item 3 of this statement, which is incorporated herein by reference. Item 8 Identification and Classification of Members of the Group: N/A Item 9 Notice of Dissolution of a Group: N/A Item 10 Certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. Signature: After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. 02/09/2008 Date Invesco Ltd. By: /s/ Lisa Brinkley ------------------------------------ Lisa Brinkley Global Compliance Director
JOINT FILING AGREEMENT In accordance with Rule 13d-1(k)(l) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing of the attached Schedule 13G, and any and all amendments thereto, and expressly authorize Invesco Ltd., as the ultimate parent company of each of its undersigned subsidiaries, to file such Schedule 13G, and any and all amendments thereto, on behalf of each of them. Dated: February 9, 2008 Invesco Ltd. By: /s/ Lisa Brinkley ------------------------------------ Name: Lisa Brinkley Title: Global Compliance Director AIM Advisors, Inc. By: /s/ Todd L. Spillane ------------------------------------ Name: Todd L. Spillane Title: Chief Compliance Officer AIM Capital Management, Inc. By: /s/ Todd L. Spillane ------------------------------------ Name: Todd L. Spillane Title: Chief Compliance Officer AIM Funds Management, Inc. By: /s/ Wayne Bolton ------------------------------------ Name: Wayne Bolton Title: Vice President, Compliance & Chief Compliance Officer AIM Private Asset Management, Inc. By: /s/ Todd L. Spillane ------------------------------------ Name: Todd L. Spillane Title: Chief Compliance Officer Invessco National Trust Company By: /s/ Kevin Lyman ------------------------------------ Name: Kevin Lyman Title: Assistant General Counsel Atlantic Trust Company, N.A. By: /s/ Wayne Dewitt ------------------------------------ Name: Wayne DeWitt Title: General Counsel Invesco Hong Kong Limited By: /s/ Asha Balachandra ------------------------------------ Name: Asha Balachandra Title: Reg. Head of Legal AP
Invesco Asset Management Deutschland GmbH By: /s/ Stephanie Ehrenfried ------------------------------------ Name: Stephanie Ehrenfried Title: Head of Legal CE Invesco Asset Management Limited By: /s/ Nick Styman ------------------------------------ Name: Nick Styman Title: Director of European Compliance Invesco Asset Management S.A. By: /s/ Patrick Riviere ------------------------------------ Name: Patrick Riviere Title: Chief Regional Officer Invesco Asset Management Oesterreich GmbH By: /s/ Thomas Kraus ------------------------------------ Name: Thomas Kraus Title: Head of Sales Invesco Global Asset Management (N.A.), Inc. By: /s/ Jeffrey Kupor ------------------------------------ Name: Jeffrey Kupor Title: Head of Legal WW Institutional Invesco GT Management Company S.A. By: /s/ Nick Styman ------------------------------------ Name: Nick Styman Title: Director of European Compliance Invesco Institutional (N.A.), Inc. By: /s/ Jeffrey Kupor ------------------------------------ Name: Jeffrey Kupor Title: Head of Legal WW Institutional Invesco Management S.A. By: /s/ Alain Gerbaldi ------------------------------------ Name: Alain Gerbaldi Title: Head of Performance Measurement & Risk Analysis Invesco Maximum Income Management S.A. By: /s/ Alain Gerbaldi ------------------------------------ Name: Alain Gerbaldi Title: Head of Performance Measurement & Risk Analysis Invesco Private Capital, Inc. By: /s/ Jeffrey Kupor ------------------------------------ Name: Jeffrey Kupor Title: Head of Legal WW Institutional