Sec Form 4 Filing - Spring Mountain Capital, LLC @ AMERICAN POWER GROUP Corp - 2017-12-19

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 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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1. Name and Address of Reporting Person Spring Mountain Capital, LLC 2. Issuer Name and Ticker or Trading Symbol AMERICAN POWER GROUP Corp [ APGI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SPRING MOUNTAIN CAPITAL, 650 MADISON AVENUE, 20TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 12/19/2017 (Street) NEW YORK, NY10022 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 12/19/2017 S( 1 ) 1,947,370 D 0 D Common Stock 12/19/2017 S( 3 )( 4 ) 4,123,095 D 0 I See Footnotes ( 3 ) ( 4 ) Common Stock 12/19/2017 S( 5 ) 5,077,704 D 0 I See Footnotes ( 5 ) Common Stock 12/19/2017 S( 6 ) 954,209 D 0 D Common Stock 12/19/2017 S( 15 ) 1,740,585 D 0 D

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 10% Convertible Preferred Stock $ 0.4 12/19/2017 S 133.3333 ( 7 ) ( 7 ) Common Stock 3,333,333 ( 2 ) 0 D ( 8 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 2,500,000 10/31/2012 05/30/2020 Common Stock 2,500,000 ( 2 ) 0 D ( 8 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 833,333 03/28/2013 09/28/2018 Common Stock 833,333 ( 2 ) 0 D ( 8 ) 10% Convertible Preferred Stock $ 0.4 12/19/2017 S 399.9999 ( 7 ) ( 7 ) Common Stock 9,999,999 ( 2 ) 0 I See Footnotes ( 9 ) ( 10 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 7,500,000 10/31/2012 05/30/2020 Common Stock 7,500,000 ( 2 ) 0 I See Footnotes ( 9 ) ( 10 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 2,499,999 03/28/2013 09/28/2018 Common Stock 2,499,999 ( 2 ) 0 I See Footnotes ( 9 ) ( 10 ) 10% Convertible Preferred Stock $ 0.4 12/19/2017 S 465.3333 ( 7 ) ( 7 ) Common Stock 11,633,332 ( 2 ) 0 I See Footnotes ( 11 ) ( 12 ) Series C Convertible Preferred Stock $ 0.2 12/19/2017 S 51.932 ( 13 ) ( 13 ) Common Stock 2,596,600 ( 2 ) 0 I See Footnotes ( 11 ) ( 12 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 8,725,000 10/31/2012 05/30/2020 Common Stock 8,725,000 ( 2 ) 0 I See Footnotes ( 11 ) ( 12 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 2,908,332 03/28/2013 09/28/2018 Common Stock 2,908,332 ( 2 ) 0 I See Footnotes ( 11 ) ( 12 ) Common Stock Warrants (right to buy) $ 0.2 12/19/2017 S 2,596,575 10/21/2016 10/21/2020 Common Stock 2,596,575 ( 2 ) 0 I See Footnotes ( 11 ) ( 12 ) 10% Convertible Preferred Stock $ 0.4 12/19/2017 S 65.3333 ( 7 ) ( 7 ) Common Stock 1,633,333 ( 2 ) 0 D ( 14 ) Series C Convertible Preferred Stock $ 0.2 12/19/2017 S 51.932 ( 13 ) ( 13 ) Common Stock 2,596,600 ( 2 ) 0 D ( 14 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 1,225,000 10/31/2012 05/30/2020 Common Stock 1,225,000 ( 2 ) 0 D ( 14 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 408,333 03/28/2013 09/28/2018 Common Stock 408,333 ( 2 ) 0 D ( 14 ) Common Stock Warrants (right to buy) $ 0.2 12/19/2017 S 2,596,575 10/21/2016 10/21/2020 Common Stock 2,596,575 ( 2 ) 0 D ( 14 ) 10% Convertible Preferred Stock $ 0.4 12/19/2017 S 213.3333 ( 7 ) ( 7 ) Common Stock 5,333,333 ( 2 ) 0 D ( 16 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 4,000,000 10/31/2012 05/30/2020 Common Stock 4,000,000 ( 2 ) 0 D ( 16 ) Common Stock Warrants (right to buy) $ 0.5 12/19/2017 S 1,333,333 03/28/2013 09/28/2018 Common Stock 1,333,333 ( 2 ) 0 D ( 16 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Spring Mountain Capital, LLC C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X SMC Select Co-Investment Fund I LP C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X SMC Select Co-Investment I GP, LLC C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X Spring Mountain Capital G.P., LLC C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X Spring Mountain Capital, LP C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X SMC Employees Partnership C/O SPRIN G MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X Steffens John C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X Ho Gregory P. C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X SMC Reserve Fund II, LP C/O SPRING MOUNTAIN CAPITAL 650 MADISON AVENUE, 20TH FLOOR NEW YORK, NY10022 X Signatures SPRING MOUNTAIN CAPITAL, LLC, By: /s/ Gregory P. Ho, Managing Member 12/21/2017 Signature of Reporting Person Date SMC SELECT CO-INVESTMENT FUND I, LP, By: SMC Select Co-Investment I GP, LLC, General Partner, By: Spring Mountain Capital G.P., LLC, Member, /s/ Gregory P. Ho, Managing Member 12/21/2017 Signature of Reporting Person Date SMC SELECT CO-INVESTMENT I GP, LLC, By: Spring Mountain Capital G.P., LLC, Member, /s/ Gregory P. Ho, Managing Member 12/21/2017 Signature of Reporting Person Date SPRING MOUNTAIN CAPITAL G.P., LLC, By: /s/ Gregory P. Ho, Managing Member 12/21/2017 Signature of Reporting Person Date SPRING MOUNTAIN CAPITAL, LP, By: Spring Mountain Capital, LLC, General Partner, /s/ Gregory P. Ho, Managing Member 12/21/2017 Signature of Reporting Person Date SMC EMPLOYEES PARTNERSHIP, By: /s/ Gregory P. Ho, Authorized Signatory 12/21/2017 Signature of Reporting Person Date /s/ John L. Steffens 12/21/2017 Signature of Reporting Person Date /s/ Gregory P. Ho 12/21/2017 Signature of Reporting Person Date SMC RESERVE FUND II, LP, By: Spring Mountain Capital G.P., LLC, General Partner, /s/ Gregory P. Ho, Managing Member 12/21/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )SMC Select Co-Investment Fund I, LP ("SMC Co-Investment") sold 1,947,370 shares of the Issuer's common stock, par $0.01 par value per share ("Common Stock"). SMC Select Co-Investment I GP, LLC is the general partner of SMC Co-Investment ("SMC Co-Investment GP") and pursuant to Rule 16a-1 of the Securities Exchange Act of 1934, as amended, it may be deemed to have been the beneficial owner of any securities reported herein that were beneficially owned by SMC Co-Investment. SMC Co-Investment GP disclaims beneficial ownership with respect to any shares of Common Stock except to the extent of its pecuniary interest therein. ( 2 )All securities reported on this Form 4 were sold for an aggregate purchase price of $4.00. ( 3 )Spring Mountain Capital G.P., LLC ("Spring Mountain GP") is the general partner to SMC Reserve Fund II, LP ("SMC Reserve II") and SMC Reserve Fund II Offshore, LP ("SMC Reserve II Offshore"), which is not a reporting person, and is the sole member of SMC Co-Investment GP. Entities over which Spring Mountain GP is deemed to have voting and investment sold 4,123,095 shares of Common Stock. Spring Mountain Capital, LP ("SMC LP") acts as investment manager to SMC Reserve II, SMC Reserve II Offshore and SMC Co-Investment. Spring Mountain Capital, LLC ("SMC LLC") is the general partner of SMC LP. ( 4 )Pursuant to Rule 16a-1 of the Securities Exchange Act of 1934, as amended, each of Spring Mountain GP, SMC LP and SMC LLC may be deemed to have been the beneficial owner of any securities reported herein that were beneficially owned by SMC Reserve II, SMC Reserve II Offshore and SMC Co-Investment. Each of Spring Mountain GP, SMC LP and SMC LLC disclaims beneficial ownership with respect to any shares of common stock except to the extent of its pecuniary interest therein. ( 5 )Mr. John L. Steffens and Mr. Gregory P. Ho are managing members of Spring Mountain GP and SMC LLC, and are also partners in SMC Employees Partnership ("SMC EP"). Entities over which Mr. Steffens and Mr. Ho are deemed to have voting and investment control sold an aggregate of 5,077,704 shares of Common Stock. Pursuant to Rule 16a-1 of the Securities Exchange Act of 1934, as amended, each of Mr. Steffens and Mr. Ho may be deemed to have been the beneficial owner of any securities reported herein that may be deemed to have been beneficially owned by SMC Reserve II, SMC Reserve II Offshore, SMC Co-Investment and SMC EP. Each of Mr. Steffens and Mr. Ho disclaims beneficial ownership with respect to any shares of common stock except to the extent of his pecuniary interest therein. ( 6 )SMC EP sold 954,209 shares of Common Stock. ( 7 )The 10% Convertible Preferred Stock ("10% Preferred Stock") is convertible at any time, at the respective holder's election and has no expiration date. ( 8 )SMC Co-Investment sold (i) 133.3333 shares of 10% Preferred Stock, which are convertible into 3,333,333 shares of Common Stock, and (ii) warrants to purchase Common Stock at an initial exercise price of $0.50 per share ("$0.50 Warrants") exercisable for up to 3,333,333 shares of Common Stock. SMC Co-Investment GP is the general partner of SMC Co-Investment SMC Co-Investment GP and pursuant to Rule 16a-1 of the Securities Exchange Act of 1934, as amended, it may be deemed to have been the beneficial owner of any securities reported herein that were beneficially owned by SMC Co-Investment. SMC Co-Investment GP disclaims beneficial ownership with respect to any shares of common stock except to the extent of its pecuniary interest therein. ( 9 )Spring Mountain GP is the general partner to SMC Reserve II and SMC Reserve II Offshore, which is not a reporting person, and is the sole member of SMC Co-Investment GP. Entities over which Spring Mountain GP is deemed to have voting and investment sold (i) 399.9999 shares of 10% Preferred Stock, which are convertible into 9,999,999 shares of Common Stock, and (ii) $0.50 Warrants exercisable for up to 9,999,999 shares of Common Stock. SMC LP acts as investment manager to SMC Reserve II, SMC Reserve II Offshore and SMC Co-Investment. SMC LLC is the general partner of SMC LP. ( 10 )Pursuant to Rule 16a-1 of the Securities Exchange Act of 1934, as amended, each of Spring Mountain GP, SMC LP and SMC LLC may be deemed to have been the beneficial owner of any securities reported herein that were beneficially owned by SMC Reserve II, SMC Reserve II Offshore and SMC Co-Investment. Each of Spring Mountain GP, SMC LP and SMC LLC disclaims beneficial ownership with respect to any shares of common stock except to the extent of its pecuniary interest therein. ( 11 )Mr. John L. Steffens and Mr. Gregory P. Ho are managing members of Spring Mountain GP and SMC LLC, and are also partners in SMC Employees Partnership ("SMC EP"). Entities over which Mr. Steffens and Mr. Ho are deemed to have voting and investment control sold (i) 465.3333 shares of 10% Preferred Stock, which are convertible into 11,633,332 shares of Common Stock, (ii) 51.9320 shares of Series C Preferred Stock, which are convertible into 2,596,600 shares of Common Stock, (iii) $0.50 Warrants exercisable for up to 11,633,332 shares of Common Stock, and (iv) warrants to purchase Common Stock at an initial exercise price of $0.20 per share ("$0.20 Warrants") exercisable for up to 2,596,575 shares of Common Stock. ( 12 )Pursuant to Rule 16a-1 of the Securities Exchange Act of 1934, as amended, each of Mr. Steffens and Mr. Ho may be deemed to have been the beneficial owner of any securities reported herein that may be deemed to have been beneficially owned by SMC Reserve II, SMC Reserve II Offshore, SMC Co-Investment and SMC EP. Each of Mr. Steffens and Mr. Ho disclaims beneficial ownership with respect to any shares of common stock except to the extent of his pecuniary interest therein. ( 13 )The Series C Convertible Preferred Stock ("Series C Preferred Stock") is convertible at any time, at the respective holder's election and has no expiration date. ( 14 )SMC EP sold (i) 65.3333 shares of 10% Preferred Stock, which are convertible into 1,633,333 shares of Common Stock, (ii) 51.9320 shares of Series C Preferred Stock, which are convertible into 2,596,600 shares of Common Stock, (iii) $0.50 Warrants exercisable for up to 1,633,333 shares of Common Stock, and (iv) $0.20 Warrants exercisable for up to 2,596,575 shares of Common Stock. ( 15 )SMC Reserve II sold 1,740,585 shares of Common Stock. ( 16 )SMC Reserve II sold (i) 213.3333 shares of 10% Preferred Stock, which are convertible into 5,333,333 shares of Common Stock, and (ii) $0.50 Warrants exercisable for up to 5,333,333 shares of Common Stock.

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* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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