Apple CEO Tim Cook received a one-time stock award worth nearly $400 million, the largest given by a company in a decade.

Apple shares hit an all-time high of $427.75 yesterday before closing down 0.16 percent at $421.73.

The company’s board granted Cook 1 million restricted stock units to signal its confidence in Cook after Steve Jobs turned over the helm of the iPhone and iPad maker to his long-time lieutenant in August.

The stock award, half of which vests in 2016 and the remaining half in 2021, was worth more than $376 million, based on the closing price of Apple’s shares on Aug. 24, 2011, the company said yesterday in a proxy filing.

“As far as a singular award, we haven’t seen anything this large in a long time,” said Aaron Boyd, head of research at Equilar, an executive compensation data firm.

The only one-time stock award in recent memory that was worth more, said Boyd, was the January 2000 stock option package that Apple gave co-founder Jobs. The 40 million options in that award were valued at more than $600 million at the time, Boyd said.