Legendary investor Warren Buffett will leave the board of publisher Washington Post Co , the company said on Thursday, ending a formal association that dates back nearly 40 years.

Buffett will serve until his term expires in May, the company said. He has been on the Post Co.'s board since 1974, minus an eight-year break when he served on the board of media company Capital Cities.

The billionaire investor's relationship to the company extended well beyond his board seat, though. He was one of the closest confidants of former Post publisher Katherine Graham; stories have described him as her business tutor and her as his entrance into high society.

Her son, Post Chief Executive Donald Graham, said the company would still consult Buffett on corporate matters.

Only our cholesterol levels will be better going forward, Graham said in a statement -- a nod to Buffett's well-known penchant for fast food lunches.

Buffett has been scaling back on board seats in recent years, choosing to devote more time to his firm Berkshire Hathaway .

(Reporting by Ben Berkowitz; Editing by Derek Caney)