UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 1) SANGSTAT MEDICAL CORPORATION ----------------------------------------------------------- (Name of Issuer) Common Stock ----------------------------------------------------------- (Title of Class of Securities) 801003104 ----------------------------------------------------------- (CUSIP Number) December 31, 2001 ----------------------------------------------------------- (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) ----------------------------------------------------------- 1 Names of Reporting Persons I.R.S. Identification Nos. of above persons (entities only). UBS AG 98-0186363 ----------------------------------------------------------- 2 Check the Appropriate Box if a Member of a Group a / / b / / See Item 8 of attached schedule. ----------------------------------------------------------- 3 SEC USE ONLY ----------------------------------------------------------- 4 Citizenship or Place of Organization - Switzerland ----------------------------------------------------------- Number of 5. Sole Voting Power ___*___ Shares Bene- 6. Shared Voting Power ___*___ ficially 7. Sole Dispositive Power ____*___ Owned by Each 8. Shared Dispositive Power ___*___ Reporting Person With: ----------------------------------------------------------- 9 Aggregate Amount Beneficially Owned by Each Reporting Person: ___*___ shares ----------------------------------------------------------- 10 Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) ----------------------------------------------------------- 11 Percent of Class Represented by Amount in Row (9) ___*___% ----------------------------------------------------------- 12 Type of Reporting Person (See Instructions) BK See Item 3 of attached schedule. ----------------------------------------------------------- * See Item 5 of attached schedule ----------------------------------------------------------- Item 1(a). Name of Issuer: SANGSTAT MEDICAL CORPORATION Item 1(b). Address of Issuer's Principal Executive Offices: 6300 Dumbarton Circle Fremont, CA 94555 ----------------------------------------------------------- Item 2(a) Name of Person Filing: UBS AG ("UBSAG"). Item 2(b) Address of Principal Business Office or, if none, Residence: Bahnhofstrasse 45 8021, Zurich, Switzerland Item 2(c) Citizenship: Switzerland Item 2(d) Title of Class of Securities: Common Stock Item 2(e) CUSIP Number: 801003104 ----------------------------------------------------------- Item 3. Type of Person Filing: UBS AG is classified as a Bank as defined in section 3(a)(6) of the Act pursuant to no action relief granted by the staff of the Securities and Exchange Commission. ----------------------------------------------------------- Item 4 (a)-(c)(iv). Ownership: Incorporated by reference to Items 5-11 of the cover pages. ----------------------------------------------------------- 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 / x /. ----------------------------------------------------------- Item 6. Ownership of More than Five Percent on Behalf of Another Person: Not applicable ----------------------------------------------------------- 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: 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 14, 2002 UBS AG By: /s/ Robert C. Dinerstein By: /s/ Robert B. Mills Robert C. Dinerstein Robert B. Mills Managing Director Managing Director