The Yale University endowment, long regarded as a suc-cessful model for fund management, lost at least 25 per cent in value in the four months to the end of October and is unlikely to show any return next year.

The loss, revealed in a letter yesterday to Yale faculty and staff, follows the news the Harvard endowment had lost at least 22 per cent since the end of June and would lose up to 30 per cent in the year to next June.