NEW YORK • Amazon.com founder and chief executive officer Jeff Bezos became a lot richer while he slept last Thursday night, after the firm reported its quarterly earnings and its shares rose 20.1 per cent.

The stock jump added US$8 billion (S$11 billion) to Mr Bezos' net worth as the market opened last Friday but, by mid-afternoon, he had given back US$3.1 billion of that gain. The shares, which hit a record high of US$580.57 overnight, stabilised near US$540. For the week, the shares rose 9.6 per cent.

Mr Bezos owned 83.92 million shares, or roughly 18 per cent of Amazon's outstanding stock, as of May 14.

His stake easily dwarfs those of other insiders. Mr Diego Piacentini, senior vice-president of international consumer business, is the second-largest insider holder behind Mr Bezos, with 110,000 shares.

The stake held by Mr Bezos would hold a market cap of about US$48.6 billion on its own, which is bigger than S&P 500 names such as FedEx, Caterpillar and Netflix.

It is too soon to tell whether Mr Bezos was up overnight selling some of his highest-priced shares, but an examination of his filings with the US Securities and Exchange Commission shows he has been slowly cutting his stake, mainly by donating stock to charity.

He owns roughly 5 per cent fewer shares now than his 88.1 million as of Aug 1, 2011.

REUTERS