Citigroup has a policy of not buying stock from its employees, but said it had made an a exception in Weill's case as such an unusually large block of shares could have depressed the price when sold. The bank said the 5.6m shares were purchased at $47.14 each. Weill, 70, resigned as chief executive three months early to hand over the reins to his long-time ally and confidant Charles Prince, head of Citigroup's corporate and investment bank.