X0303 4 2010-03-26 0001257640 KRONOS WORLDWIDE INC KRO 0000024240 CONTRAN CORP 5430 LBJ FREEWAY, SUITE 1700 DALLAS TX 75240 0 0 1 0 0001037854 SIMMONS HAROLD C 5430 LBJ FREEWAY, SUITE 1700 DALLAS TX 75240 1 1 1 0 Chairman of the Board Common Stock $0.01 par value 2010-03-26 4 P 0 285 15.20 A 2686 D Common Stock $0.01 par value 79567 I by TFMC Common Stock $0.01 par value 28995021 I by Valhi Common Stock $0.01 par value 17609635 I by NL Directly held by TIMET Finance Management Company. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationships to the persons joining in this filing. Directly held by Valhi, Inc. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationships to the persons joining in this filing. Directly held by NL Industries, Inc. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship to the persons joining in this filing. Mr. Harold C. Simmons and his spouse directly hold 235,509 and 54,856 shares, respectively, of the common stock of the issuer. Mr. Simmons disclaims beneficial ownership of the shares of the issuer's common stock that his spouse owns. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationships of Mr. Simmons to the other persons joining in this filing. Exhibit Index: Exhibit 99 - Additional Information A. Andrew R. Louis. Secretary, for Contran Corporation 2010-03-30 A. Andrew R. Louis. Attorney-in-fact, for Harold C. Simmons 2010-03-30