BMG announced Jan. 13 that Arista president and CEO Antonio ''L.A.'' Reid, 48, would step down, effective immediately. The artist-friendly Reid, who assumed control of Arista after the controversial 2000 ouster of label vet Clive Davis, shepherded the careers of such stars as Usher, Pink, Avril Lavigne, and OutKast to multiplatinum success. In a statement, BMG chief Rolf Schmidt-Holz said Reid was ''one of the music industry's top record men. His passion for working with and developing some of the world's best artists is unparalleled.'' Nonetheless, questions remain about the unexpected departure, fueling rumors that Arista will be folded into the RCA Records Group, now headed by Davis, following the impending Sony/BMG merger. Reid could not be reached for comment, but label superstar Whitney Houston told EW, ''I have known and worked with L.A. Reid over the years and wish him only the best always.''