Page 1 of 15 Pages UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1)* SONUS PHARMACEUTICALS, INC. (Name of Issuer) COMMON STOCK (Title of Class of Securities) 835692104 (CUSIP Number) *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). CUSIP No. 835692104 Page 2 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Aperture Associates, L.P. 94-3128732 - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - --------------------------------------------------------------- (5) SOLE VOTING POWER 448,334 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 0 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 448,334 ----------------------------------- (8) SHARED DISPOSITIVE POWER 0 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 448,334 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 5.2% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* PN - --------------------------------------------------------------- CUSIP No. 835692104 Page 3 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Horsley Bridge Partners, Inc. 16-1193261 - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - --------------------------------------------------------------- (5) SOLE VOTING POWER 0 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 574,783 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 0 ----------------------------------- (8) SHARED DISPOSITIVE POWER 574,783 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 574,783 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 6.7% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* IA, CO - --------------------------------------------------------------- CUSIP No. 835692104 Page 4 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Kevin P. Wright ###-##-#### - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. - --------------------------------------------------------------- (5) SOLE VOTING POWER 0 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 448,334 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 0 ----------------------------------- (8) SHARED DISPOSITIVE POWER 448,334 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 448,334 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 5.2% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* IN - --------------------------------------------------------------- CUSIP No. 835692104 Page 5 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Aperture Partners, L.P. 94-3128731 - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware - --------------------------------------------------------------- (5) SOLE VOTING POWER 0 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 448,334 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 0 ----------------------------------- (8) SHARED DISPOSITIVE POWER 448,334 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 448,334 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 5.2% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* PN - --------------------------------------------------------------- CUSIP No. 835692104 Page 6 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON S. Phillip Horsley ###-##-#### - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. - --------------------------------------------------------------- (5) SOLE VOTING POWER 0 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 574,783 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 0 ----------------------------------- (8) SHARED DISPOSITIVE POWER 574,783 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 574,783 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 6.7% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* IN - --------------------------------------------------------------- CUSIP No. 835692104 Page 7 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Gary L. Bridge ###-##-#### - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. - --------------------------------------------------------------- (5) SOLE VOTING POWER 0 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 574,783 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 0 ----------------------------------- (8) SHARED DISPOSITIVE POWER 574,783 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 574,783 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 6.7% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* IN - --------------------------------------------------------------- CUSIP No. 835692104 Page 8 of 15 pages - --------------------------------------------------------------- (1) NAME OF REPORTING PERSON S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON N. Dan Reeve ###-##-#### - ---------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* Instructions) (a) / / (b) /x/ - --------------------------------------------------------------- (3) SEC USE ONLY - --------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. - --------------------------------------------------------------- (5) SOLE VOTING POWER 0 ----------------------------------- NUMBER OF SHARES (6) SHARED VOTING POWER BENEFICIALLY OWNED BY 448,334 EACH REPORTING PERSON----------------------------------- WITH (7) SOLE DISPOSITIVE POWER 0 ----------------------------------- (8) SHARED DISPOSITIVE POWER 448,334 - --------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 448,334 - --------------------------------------------------------------- (10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* / / - --------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 5.2% - --------------------------------------------------------------- (12) TYPE OF REPORTING PERSON* IN - --------------------------------------------------------------- Page 9 of 15 Pages ITEM 1. (a) NAME OF ISSUER. Sonus Pharmaceuticals, Inc. (b) ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES. 22026 20th Avenue Southeast Suite 102 Bothell, Washington 98021 ITEM 2. (a) NAME OF PERSON FILING. Pursuant to Rule 13d-1(f)(1) of Regulation 13D-G of the General Rules and Regulations under the Securities Exchange Act of 1934, as amended (the "Act"), the undersigned hereby file this Schedule 13G Amendment No. 1 on behalf of Aperture Associates, L.P. ("Aperture"), Horsley Bridge Partners, Inc. ("HBP"), Kevin P. Wright ("Wright"), Aperture Partners, L.P. ("Aperture Partners"), S. Phillip Horsley ("Horsley"), Gary L. Bridge ("Bridge") and N. Dan Reeve ("Reeve"). Aperture, HBP, Wright, Aperture Partners, Horsley, Bridge and Reeve are sometimes hereinafter collectively referred to as the "Reporting Persons." (b) ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE. The principal business office of Aperture, HBP, Aperture Partners, Horsley, Bridge and Reeve is: 505 Montgomery Street San Francisco, California 94111 The principal business office of Wright is: Venture Capital Development Eastman Kodak Company Building 83, Room 716 1999 Lake Avenue Rochester, New York 14650 (c) CITIZENSHIP. Each of Aperture, HBP and Aperture Partners is organized in the State of Delaware. Each of Wright, Horsley, Bridge and Reeve is a citizen of the U.S.A. Page 10 of 15 Pages (d) TITLE OF CLASS OF SECURITY. Common Stock (e) CUSIP NUMBER. 835692104 ITEM 3. Not applicable. ITEM 4. OWNERSHIP. With respect to Aperture: (a) Amount Beneficially Owned: 448,334 (b) Percent of Class: 5.2% (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: 448,334 (ii) shared power to vote or to direct the vote: None (iii) sole power to dispose or to direct the disposition of: 448,334 (iv) shared power to dispose or to direct the disposition of: None With respect to Wright, Aperature Partners and Reeve: (a) Amount Beneficially Owned: 448,334 (b) Percent of Class: 5.2% (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: None (ii) shared power to vote or to direct the vote: 448,334 Page 11 of 15 Pages (iii) sole power to dispose or to direct the disposition of: None (iv) shared power to dispose or to direct the disposition of: 448,334 With respect to HBP, Horsley and Bridge: (a) Amount Beneficially Owned: 574,783 (b) Percent of Class: 6.7% (c) Number of shares as to which such person has: (i) sole power to vote or to direct the vote: None (ii) shared power to vote or to direct the vote: 574,783 (iii) sole power to dispose or to direct the disposition of: None (iv) shared power to dispose or to direct the disposition of: 574,783 This statement relates to shares of Common Stock and warrants of the Issuer which are held by Aperture and Horsley Bridge Fund II, L.P., a Delaware limited partnership ("HB Fund II"). HBP, Wright and Aperture Partners are the general partners of Aperture. The power to vote or to direct the vote and to dispose or to direct the disposition of such Common Stock is exercised by the general partners of Aperture through a Management Committee comprised of Wright, Horsley, Bridge and Reeve. Horsley and Bridge are the trustees of certain family trusts which own all of the stock of HBP and are the directors of HBP. In addition, Horsley and Bridge are two of the three general partners of Aperture Partners. Reeve is an employee of HBP and is the third general partner of Aperture Partners. HBP and HBF Partners II, L.P., a Delaware limited partnership, are the general partners of HB Fund II. Mr. Horsley and Mr. Bridge are the general partners of HBF Partners II, L.P. The power to vote or to direct the voting and to dispose or to direct the disposition of the Common Stock held by HB Fund II is held by HBP, which acts as the Managing General Partner of HB Page 12 of 15 Pages Fund II pursuant to the terms of the Partnership Agreement. Mr. Horsley and Mr. Bridge, who are the trustees of certain family trusts which own all of the stock of HBP and are the directors of HBP, may be deemed to share the voting and dispositive power held by HBP. Mr. Horsley and Mr. Bridge also may be deemed to share such voting and dispositive power because of their status as general partners of HBF Partners II, L.P., which also serves as a general partner of HB Fund II. The business address of HB Fund II and HBF Partners II, L.P. is: 505 Montgomery Street, San Francisco, California 94111. As of December 31, 1996, Aperture owned 395,976 shares of Common Stock of Sonus Pharmaceuticals, Inc. and warrants, which were then exercisable, for the purchase of an additional 52,358 shares of Common Stock of Sonus Pharmaceuticals, Inc. These holdings have previously been reported on a Schedule 13G filed with the Securities and Exchange Commission on January 24, 1996. The subsequent acquisitions of Common Stock of the Issuer that are being reported pursuant to this statement on Schedule 13G were not cash purchases, but rather were the result of the receipt of 126,449 shares of Common Stock of the Issuer by HB Fund II in a distribution from Enterprise Partners II, L.P., a limited partnership in which HB Fund II is a limited partner. Pursuant to Rule 13d-4 of Regulation 13D-G of the General Rules and Regulations under the Act: Aperture Partners, Horsley, Bridge and Reeve each disclaim beneficial ownership of the Common Stock of the Issuer owned by Aperature; Horsley and Bridge each disclaim beneficial ownership of the Common Stock of the Issuer owned by HB Fund II; and the filing of this Statement by such Reporting Persons shall not be construed as an admission that such Reporting Persons are, for the purposes of Section 13(d) or 13(g) of the Act, beneficial owners of such Common Stock. ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS. Not Applicable. ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON. Not applicable. Page 13 of 15 Pages ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY. Not applicable. ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP. Not applicable. ITEM 9. NOTICE OF DISSOLUTION OF GROUP. Not applicable. ITEM 10. CERTIFICATION. Not applicable. [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK] Page 14 of 15 Pages 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. Dated: February 13, 1997 APERTURE ASSOCIATES, L.P. By: Horsley Bridge Partners, Inc. Its: General Partner By: /S/ PHILLIP HORSLEY Phillip Horsley Its: President HORSLEY BRIDGE PARTNERS, INC. By: /S/ PHILLIP HORSLEY Phillip Horsley Its: President /S/ KEVIN P. WRIGHT KEVIN P. WRIGHT APERTURE PARTNERS, L.P. By: /S/ PHILLIP HORSLEY Phillip Horsley Its: General Partner /S/ PHILLIP HORSLEY PHILLIP HORSLEY /S/ GARY L. BRIDGE GARY L. BRIDGE /S/ N. DAN REEVE N. DAN REEVE