Charlie Munger, who helped Warren Buffett build Berkshire Hathaway into an investment powerhouse, has died at a California hospital. He was 99.

Berkshire Hathaway said in a statement that Munger’s family told the company that he died Tuesday morning at the hospital just over a month before his 100th birthday.

“Berkshire Hathaway could not have been built to its present status without Charlie’s inspiration, wisdom and participation,” Buffett said in a statement. The famous investor also devoted part of his annual letter to Berkshire shareholders earlier this year to a tribute to Munger.

Munger served as Buffett’s sounding board on investments and business decisions and helped lead Berkshire for more than five decades and served as its longtime vice chairman.

Munger had been using a wheelchair to get around for several years but he had remained mentally sharp. That was on display while he fielded hours of questions at the annual meetings of Berkshire and the Daily Journal Corp. earlier this year, and in recent interviews on an investing podcast and also with The Wall Street Journal and CNBC.

But Buffett always credited Munger with pushing him beyond his early value investing strategies to buy great businesses at good prices like See’s Candy.