Warren Buffett’s Berkshire Hathaway lost its triple-A grade from Moody’s Investors Service, the very ratings firm in which the billionaire holds a 20 per cent stake.

The downgrade, which follows Fitch Ratings’ one-notch cut last month, comes as Berkshire seeks to rebound from its worst year since the “Sage of Omaha” took control of the former textiles maker in 1965. Moody’s dropped Berkshire two notches, to double-A2.