Martin Leibowitz will become managing director of U.S. equity strategy at Morgan Stanley & Co., New York, effective March 1. It is a new position. Mr. Leibowitz will retire as vice chairman and chief investment officer of TIAA-CREF, New York, at the end of the month. Stephanie Cohen Glass, TIAA-CREF spokeswoman, said a replacement for Mr. Leibowitz has not been found, but internal and external candidates are being considered. Mr. Leibowitz joined TIAA-CREF in 1995 after 26 years at Salomon Brothers.