SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13D (Rule 13d-101) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a) (Amendment No. 4)1 LabOne, Inc. ---------------------------------- (Name of Issuer) Common Stock, $.01 par value ------------------------------------------ (Title of Class of Securities) 50540L 10 5 ---------------------------------- (CUSIP Number) Welsh, Carson, Anderson & Stowe Othon A. Prounis, Esq. 320 Park Avenue, Suite 2500 Ropes & Gray LLP New York, New York 10023 45 Rockefeller Plaza Attention: Jonathan M. Rather New York, New York 10111 Tel. (212) 893-9500 Tel. (212) 841-5700 --------------------------------------------------------- (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) December 5, 2003 ---------------------------------------------------------- (Date of Event Which Requires Filing of This Statement) If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box [ ]. ----------------------- 1 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 disclosures provided in a prior cover page. The information required on 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 or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act. CUSIP No. 50540L 10 5 Page 2 of 6 Pages 1) Name of Reporting Person: Welsh, Carson, Anderson & Stowe IX, L.P. and I.R.S. Identification No. of Above Person, if an Entity (Voluntary): ------------------------------------------------------------- 2) Check the Appropriate Box (a) [X] if a Member of a Group (b) [ ] ------------------------------------------------------------- 3) SEC Use Only ------------------------------------------------------------- 4) Source of Funds Not Applicable ------------------------------------------------------------- 5) Check if Disclosure of Legal Proceedings Is Not Applicable Required Pursuant to Items 2(d) or 2(e) ------------------------------------------------------------- 6) Citizenship or Place of Organization Delaware ------------------------------------------------------------- Number of 7) Sole Voting -0- Shares Beneficially Power Owned by Reporting Person: --------------------------------------- 8) Shared Voting Power -0- --------------------------------------- 9) Sole Disposi- -0- tive Power --------------------------------------- 10) Shared Dis- positive Power -0- --------------------------------------- 11) Aggregate Amount Beneficially -0- Owned by Each Reporting Person ------------------------------------------------------------------------ 12) Check if the Aggregate Amount in Row (11) Excludes Certain Shares ------------------------------------------------------------------------ 13) Percent of Class Represented by -0- Amount in Row (11) ------------------------------------------------------------------------ 14) Type of Reporting Person PN CUSIP No. 50540L 10 5 Page 3 of 6 Pages 1) Name of Reporting Person: WCAS Management Corporation and I.R.S. Identification No. of Above Person, if an Entity (Voluntary): ------------------------------------------------------------------------ 2) Check the Appropriate Box (a) [X] if a Member of a Group (b) [ ] ------------------------------------------------------------------------ 3) SEC Use Only ------------------------------------------------------------------------ 4) Source of Funds Not Applicable ------------------------------------------------------------------------ 5) Check if Disclosure of Legal Proceedings Is Not Applicable Required Pursuant to Items 2(d) or 2(e) ------------------------------------------------------------------------ 6) Citizenship or Place of Organization Delaware ------------------------------------------------------------------------ Number of 7) Sole Voting 1,478 shares of Shares Beneficially Power Common Stock Owned by Reporting Person: ------------------------------------------ 8) Shared Voting Power -0- ------------------------------------------ 9) Sole Disposi- 1,478 shares of tive Power Common Stock ------------------------------------------ 10) Shared Dis- positive Power -0- ------------------------------------------ 11) Aggregate Amount Beneficially 1,478 shares of Owned by Each Reporting Person Common Stock -------------------------------------------------------------------------- 12) Check if the Aggregate Amount in Row (11) Excludes Certain Shares -------------------------------------------------------------------------- 13) Percent of Class Represented by less than 0.1% Amount in Row (11) -------------------------------------------------------------------------- 14) Type of Reporting Person CO CUSIP No. 50540L 10 5 Page 4 of 6 Pages Amendment No. 4 to Schedule 13D (Final Amendment) ------------------------------------------------- Reference is hereby made to the statement on Schedule 13D filed with the Securities and Exchange Commission (the "Commission") on behalf of the Reporting Persons on September 10, 2001, Amendment No. 1 thereto filed on June 12, 2003 200, Amendment No. 2 thereto filed on September 26, 2003 and Amendment No. 3 thereto filed on November 13, 2003 (as so amended, the "Schedule 13D"). Terms defined in the Schedule 13D are used herein as so defined. The following items of the Schedule 13D are hereby amended as follows: Item 5. Interest in Securities of the Issuer ------------------------------------ Item 5 is hereby amended and restated to read in its entirety as follows: The following information is based on a total of 12,843,152 shares of Common Stock outstanding as of October 31, 2003, as reported in the Issuer's Report on Form 10-Q for the period ended September 30, 2003 filed with the Commission on November 13, 2003. All shares of Series B-1 Preferred held by each entity and person named below have been converted to Common Stock. (a) WCAS IX and IX Associates ------------------------- WCAS IX and IX Associates own no shares of Common Stock. WCAS Management --------------- WCAS Management owns 1,478 shares of Common Stock, or less than 0.1% of the Common Stock outstanding. Managing Members of IX Associates and Stockholders of WCAS Management ------------------------------------- (i) Patrick J. Welsh owns 24,149 shares of Common Stock, or approximately 0.2% of the Common Stock outstanding. (ii) Russell L. Carson owns 24,550 shares of Common Stock, or approximately 0.2% of the Common Stock outstanding. (iii) Bruce K. Anderson owns 23,989 shares of Common Stock, or approximately 0.2% of the Common Stock outstanding. (iv) Thomas E. McInerney owns 24,440 shares of Common Stock, or approximately 0.2% of the Common Stock outstanding. (v) Robert A. Minicucci owns 24,440 shares of Common Stock, or approximately 0.2% of the Common Stock outstanding. (vi) Anthony J. de Nicola directly beneficially owns 18,037 shares of Common Stock, indirectly beneficially owns (through deNicola Holdings L.P.) 388 shares of Common Stock and indirectly beneficially owns (through three trusts for the benefit of his children) 216 shares of Common Stock, or in the aggregate 18,641 shares of Common Stock or approximately 0.2% of the Common Stock outstanding. CUSIP No. 50540L 10 5 Page 5 of 6 Pages (vii) Paul B. Queally owns 15,292 shares of Common Stock, or approximately 0.1% of the Common Stock outstanding. (viii) Jonathan M. Rather owns 4,506 shares of Common Stock (including shares held in his IRA account), or less than 0.1% of the Common Stock outstanding. (ix) D. Scott Mackesy owns 4,105 shares of Common Stock, or less than 0.1% of the Common Stock outstanding. (x) Sanjay Swani owns 1,533 shares of Common Stock, or less than 0.1% of the Common Stock outstanding. (xi) John D. Clark owns 1,533 shares of Common Stock, or less than 0.1% of the Common Stock outstanding. (xii) James R. Matthews owns 1,533 shares of Common Stock (including shares held in his IRA account), or less than 0.1% of the Common Stock outstanding. (b) The managing members of IX Associates and the stockholders of WCAS Management may be deemed to share the power to vote or direct the voting of and to dispose or direct the disposition of the securities of the Issuer owned by WCAS IX and WCAS Management, respectively. Each of the managing members of IX Associates and the stockholders of WCAS Management disclaims beneficial ownership of all securities other than those he owns directly or by virtue of his indirect pro rata interest, as a managing member of IX Associates and/or a stockholder of WCAS Management, in the securities owned by WCAS IX and/or WCAS Management. (c) On December 5, 2003 WCAS IX distributed 2,350,102 shares of Common Stock to its partners, including 23,517 shares to IX Associates, immediately followed by the distribution of such 23,517 shares to the members of IX Associates. (d) Except as described in this statement, no person has or had the power to direct the receipt of dividends on or the proceeds of sales of the shares of Common Stock owned or formerly owned by WCAS IX or WCAS Management. (e) The Reporting Persons ceased to be the beneficial owners of less than five percent of the Common Stock on December 5, 2003. CUSIP No. 50540L 10 5 Page 6 of 6 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. WELSH, CARSON, ANDERSON & STOWE IX, L.P. By: WCAS IX Associates, LLC, General Partner By: /s/ Jonathan M. Rather ----------------------- Managing Member WCAS MANAGEMENT CORPORATION By: /s/ Jonathan M. Rather ----------------------- Vice President, Secretary & Treasurer Dated: December 9, 2003