SECURITIES & EXCHANGE COMMISSION Washington, D.C. 20549 ----------------------- SCHEDULE 13G* (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULES 13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO 13d-2(b) Quidel Corp. (Name of Issuer) Common Stock, $0.001 par value (Title of Class of Securities) 74838J101 (CUSIP Number) April 10, 2001 (Date of event which requires filing of this statement) Check the appropriate box to designate the rule pursuant to which this Schedule 13G is filed: [ ] Rule 13d-1(b) [X] Rule 13d-1(c) [ ] Rule 13d-1(d) (Page 1 of 12 Pages) --------------- *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 purposes 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. 74838J101 13G Page 2 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Oracle Partners, L.P. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 1,620,500 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 1,620,500 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,620,500 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** PN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 74838J101 13G Page 3 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Oracle Institutional Partners, L.P. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 441,700 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 441,700 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 441,700 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 1.6% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** PN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 74838J101 13G Page 4 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Oracle Investment Management, Inc. ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 728,500 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 728,500 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 728,500 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 2.6% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** CO ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 74838J101 13G Page 5 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Oracle Associates, LLC ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 2,062,200 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 2,062,200 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,062,200 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 7.3% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** OO ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 74838J101 13G Page 6 of 12 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Larry N. Feinberg ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [X] (b) [ ] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States ----------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER 28,000 SHARES -------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 2,790,700 OWNED BY -------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER 28,000 REPORTING -------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 2,790,700 ----------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,818,700 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 10.0% ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN ----------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 74838J101 13G Page 7 of 12 Pages This statement on Schedule 13G amends, supplements and restates the Amendment No. 1 to Schedule 13D which was filed on November 22, 1999 with respect to the Common Stock (as defined in Item 2(d) below) of Quidel Corp. Item 1(a). Name of Issuer: The name of the issuer is Quidel Corp. (the "Company"). Item 1(b). Address of Issuer's Principal Executive Offices: The Company's principal executive office is located at 10165 McKellar Court, San Diego, California. Item 2(a). Name of Person Filing: This statement is filed by: (i) Oracle Partners, L.P., a Delaware limited partnership ("Oracle Partners"), with respect to shares of Common Stock directly owned by it; (ii) Oracle Institutional Partners, L.P., a Delaware limited partnership ("Oracle Institutional"), with respect to shares of Common Stock directly owned by it; (iii) Oracle Investment Management, Inc., a Delaware corporation (the "Investment Manager"), which serves as investment manager to and has investment discretion over the securities held by (A) SAM Oracle Investments Inc., a British Virgin Islands corporation ("SAM Oracle"), with respect to shares of Common Stock directly owned by SAM Oracle, (B) Oracle Offshore Limited, a Cayman Islands corporation ("Oracle Offshore"), with respect to shares of Common Stock directly owned by Oracle Offshore, and (C) Oracle Management, Inc. Employees Retirement Plan (the "Retirement Plan"), with respect to shares of Common Stock directly owned by the Retirement Plan; (iv) Oracle Associates, LLC, a Delaware limited liability company ("Oracle Associates"), which serves as the general partner of Oracle Partners and Oracle Institutional (together, the "Partnerships"), with respect to shares of Common Stock directly owned by the Partnerships; and (v) Mr. Larry N. Feinberg ("Mr. Feinberg"), who (A) serves as the senior managing member of Oracle Associates, (B) is the sole shareholder and president of the Investment Manager and (C) is the trustee of The Feinberg Family Foundation (the "Foundation") with respect to shares of Common Stock directly owned by him (individually and as trustee of the Foundation) and by the Partnerships, SAM Oracle, Oracle Offshore, and the Retirement Plan. CUSIP No. 74838J101 13G Page 8 of 12 Pages The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." Any disclosures herein with respect to persons other than the Reporting Persons are made on information and belief after making inquiry to the appropriate party. Item 2(b). Address of Principal Business Office or, if None, Residence: The address of the business office of each of the Reporting Persons is 200 Greenwich Avenue, 3rd Floor, Greenwich, Connecticut 06830. Item 2(c). Citizenship: Each of the Partnerships, the Investment Manager and Oracle Associates is organized under the laws of the State of Delaware. Mr. Feinberg is a citizen of the United States of America. Item 2(d). Title of Class of Securities: Common Stock, $0.001 par value ("Common Stock") Item 2(e). CUSIP Number: 74838J101 Item 3. If this statement is filed pursuant to Rules 13d-1(b) or 13d-2(b) or (c), check whether the person filing is a: (a) [ ] Broker or dealer registered under Section 15 of the Act, (b) [ ] Bank as defined in Section 3(a)(6) of the Act, (c) [ ] Insurance Company as defined in Section 3(a)(19) of the Act, (d) [ ] Investment Company registered under Section 8 of the Investment Company Act of 1940, (e) [ ] Investment Adviser in accordance with Rule 13d-1(b)(1)(ii)(E), (f) [ ] Employee Benefit Plan or Endowment Fund in accordance with 13d-1(b)(1)(ii)(F), (g) [ ] Parent Holding Company or control person in accordance with Rule 13d-1(b)(1)(ii)(G), (h) [ ] Savings Association as defined in Section 3(b) of the Federal Deposit Insurance Act, CUSIP No. 74838J101 13G Page 9 of 12 Pages (i) [ ] Church Plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940, (j) [ ] Group, in accordance with Rule 13d-1(b)(1)(ii)(J). If this statement is filed pursuant to 13d-1(c), check this box: [x] Item 4. Ownership. A. Oracle Partners, L.P. (a) Amount beneficially owned: 1,620,500 (b) Percent of class: 5.8% The percentages used herein and in the rest of this Schedule 13G are calculated based upon the 28,068,517 shares of Common Stock issued and outstanding as of March 12, 2001, as reflected in the Company's Form 10-K for the period ending December 31, 2000. (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 1,620,500 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 1,620,500 B. Oracle Institutional Partners, L.P. (a) Amount beneficially owned: 441,700 (b) Percent of class: 1.6% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 441,700 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 441,700 C. Oracle Investment Management, Inc. (a) Amount beneficially owned: 728,500 (b) Percent of class: 2.6% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 728,500 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 728,500 D. Oracle Associates, LLC (a) Amount beneficially owned: 2,062,200 (b) Percent of class: 7.3% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote: 2,062,200 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 2,062,200 CUSIP No. 74838J101 13G Page 10 of 12 Pages E. Larry N. Feinberg (a) Amount beneficially owned: 2,818,700 (b) Percent of class: 10.0% (c) Number of shares as to which such person has: (i) Sole power to vote or direct the vote: 28,000 (ii) Shared power to vote or direct the vote: 2,790,700 (iii) Sole power to dispose or direct the disposition: 28,000 (iv) Shared power to dispose or direct the disposition: 2,790,700 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. SAM Oracle, Oracle Offshore and the Retirement Plan, each clients of the Investment Manager, have the right to receive and the power to direct the receipt of dividends from, and proceeds from the sale of, the securities reported in this statement. No single client of the Investment Manager holds more than five percent of the class of securities reported herein. 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. Each of the Reporting Persons hereby makes the following certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above 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. CUSIP No. 74838J101 13G Page 11 of 12 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: April 20, 2001 /s/ Larry N. Feinberg -------------------------------------- Larry N. Feinberg, individually and as senior managing member of Oracle Associates, LLC, on behalf of itself and as the general partner of Oracle Partners, L.P. and Oracle Institutional Partners, L.P., as president of Oracle Investment Management, Inc., and as trustee of The Feinberg Family Foundation CUSIP No. 74838J101 13G Page 12 of 12 Pages EXHIBIT 1 JOINT ACQUISITION STATEMENT PURSUANT TO RULE 13d-1(k) The undersigned acknowledge and agree that the foregoing statement on Schedule 13G, is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G, shall be filed on behalf of each of the undersigned without the necessity of filing additional joint acquisition statements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate. DATED: April 20, 2001 /s/ Larry N. Feinberg -------------------------------------- Larry N. Feinberg, individually and as senior managing member of Oracle Associates, LLC, on behalf of itself and as the general partner of Oracle Partners, L.P. and Oracle Institutional Partners, L.P., as president of Oracle Investment Management, Inc., and as trustee of The Feinberg Family Foundation