SC 13G/A 1 americanpacific.txt UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 6 )* ------------------ American Pacific Corporation -------------------------------------------------------------------------------- (Name of Issuer) Common Stock -------------------------------------------------------------------------------- (Title of Class of Securities) 028740108 ------------------------------- (CUSIP Number) January 31, 2004 ------------------------------ (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). 13G CUSIP No. 028740108 ---------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON / I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Artisan Partners Limited Partnership -------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see Instructions) (a) [ ] Not Applicable (b) [ ] -------------------------------------------------------------------------------- 3 SEC USE ONLY -------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Delaware -------------------------------------------------------------------------------- 5 SOLE VOTING POWER None NUMBER OF SHARES ----------------------------------------------------------------- BENEFICIALLY 6 SHARED VOTING POWER OWNED BY EACH 420,427 REPORTING PERSON ----------------------------------------------------------------- WITH 7 SOLE DISPOSITIVE POWER None ------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 420,427 -------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 420,427 -------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable -------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% -------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) IA -------------------------------------------------------------------------------- 13G CUSIP No. 028740108 ---------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON / S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Artisan Investment Corporation -------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see Instructions) (a) [ ] Not Applicable (b) [ ] -------------------------------------------------------------------------------- 3 SEC USE ONLY -------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Wisconsin -------------------------------------------------------------------------------- 5 SOLE VOTING POWER None NUMBER OF SHARES ----------------------------------------------------------------- BENEFICIALLY 6 SHARED VOTING POWER OWNED BY EACH 420,427 REPORTING PERSON ----------------------------------------------------------------- WITH 7 SOLE DISPOSITIVE POWER None ------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 420,427 -------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 420,427 -------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable -------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% -------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) CO -------------------------------------------------------------------------------- 13G CUSIP No. 028740108 ---------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON / S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Andrew A. Ziegler -------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see Instructions) (a) [ ] Not Applicable (b) [ ] -------------------------------------------------------------------------------- 3 SEC USE ONLY -------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. -------------------------------------------------------------------------------- 5 SOLE VOTING POWER None NUMBER OF SHARES ----------------------------------------------------------------- BENEFICIALLY 6 SHARED VOTING POWER OWNED BY EACH 420,427 REPORTING PERSON ----------------------------------------------------------------- WITH 7 SOLE DISPOSITIVE POWER None ------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 420,427 -------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 420,427 -------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable -------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% -------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) IN -------------------------------------------------------------------------------- 13G CUSIP No. 028740108 ---------------- -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON / S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Carlene Murphy Ziegler -------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (see Instructions) (a) [ ] Not Applicable (b) [ ] -------------------------------------------------------------------------------- 3 SEC USE ONLY -------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION U.S.A. -------------------------------------------------------------------------------- 5 SOLE VOTING POWER None NUMBER OF SHARES ----------------------------------------------------------------- BENEFICIALLY 6 SHARED VOTING POWER OWNED BY EACH 420,427 REPORTING PERSON ----------------------------------------------------------------- WITH 7 SOLE DISPOSITIVE POWER None ------------------------------------------------------------- 8 SHARED DISPOSITIVE POWER 420,427 -------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 420,427 -------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (see Instructions) Not Applicable -------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% -------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON (see Instructions) IN -------------------------------------------------------------------------------- Item 1(a) Name of Issuer: American Pacific Corporation Item 1(b) Address of Issuer's Principal Executive Offices: 3770 Howard Hughes Parkway Suite 300 Las Vegas, NV 89109 Item 2(a) Name of Person Filing: Artisan Partners Limited Partnership ("Artisan Partners") Artisan Investment Corporation, the general partner of Artisan Partners ("Artisan Corp.") Andrew A. Ziegler Carlene Murphy Ziegler Item 2(b) Address of Principal Business Office: Artisan Partners, Artisan Corp., Mr. Ziegler and Ms. Ziegler are all located at: 875 East Wisconsin Avenue, Suite 800 Milwaukee, Wisconsin 53202 Item 2(c) Citizenship: Artisan Partners is a Delaware limited partnership Artisan Corp. is a Wisconsin corporation Mr. Ziegler and Ms. Ziegler are U.S. citizens Item 2(d) Title of Class of Securities: Common Stock Item 2(e) CUSIP Number: 028740108 Item 3 Type of Person: (e) Artisan Partners is an investment adviser registered under section 203 of the Investment Advisers Act of 1940; Artisan Corp. is the General Partner of Artisan Partners; Mr. Ziegler and Ms. Ziegler are the principal stockholders of Artisan Corp. Item 4 Ownership (at January 31, 2004): (a) Amount owned "beneficially" within the meaning of rule 13d-3: 420,427 (b) Percent of class: 5.8% (based on 7,283,000 shares outstanding as of January 31, 2004) (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: 420,427 (iii) sole power to dispose or to direct the disposition of: None (iv) shared power to dispose or to direct disposition of: 420,427 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: The shares reported herein have been acquired on behalf of discretionary clients of Artisan Partners. Persons other than Artisan Partners are entitled to receive all dividends from, and proceeds from the sale of, those shares. None of those persons, to the knowledge of Artisan Partners, Artisan Corp., Mr. Ziegler or Ms. Ziegler, has an economic interest in more than 5% of the class. Item 7 Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person: 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: 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. Date: February 9, 2004 ARTISAN INVESTMENT CORPORATION for itself and as general partner of ARTISAN PARTNERS LIMITED PARTNERSHIP Janet D. Olsen* -------------------------------- ANDREW A. ZIEGLER Andrew A. Ziegler* -------------------------------- CARLENE MURPHY ZIEGLER Carlene Murphy Ziegler* -------------------------------- *By: /s/ Janet D. Olsen --------------------------- Janet D. Olsen Vice President of Artisan Investment Corporation Attorney-in-Fact for Andrew A. Ziegler Attorney-in-Fact for Carlene Murphy Ziegler Exhibit Index ------------- Exhibit 1 Joint Filing Agreement dated as of February 9, 2004 by and among Artisan Partners Limited Partnership, Artisan Investment Corporation, Andrew A. Ziegler, and Carlene Murphy Ziegler Exhibit 2 Power of Attorney of Andrew A. Ziegler dated as of April 2, 2002 Exhibit 3 Power of Attorney of Carlene M. Ziegler dated as of April 2, 2002