New York ? Former top Citigroup analyst Jack Grubman said in an e-mail that he raised his rating of AT&T stock in part because his boss agreed to help get Grubman’s daughters into an exclusive nursery school.

Citigroup chief executive Sanford Weill, in a memo to senior executives Wednesday, acknowledged that he intervened on behalf of the star telecommunications analyst and that Citigroup had pledged $1 million to the 92nd Street Y, which runs the nursery school. But he denied those steps were in exchange for the upgrade of AT&T.

“I tried to help Mr. Grubman because he was an important employee who had asked for my help,” Weill said. “Although my effort to help an employee’s children is what led me to call the 92nd Street Y, the Y is a superb institution and our support is consistent with Citigroup’s philanthropic efforts.”

Weill repeated that he never influenced Grubman’s stock research.