Is Bill Gates going to buy a bigger chunk of AutoNation?

The world’s second-richest man now has conditional approval to pursue a bigger stake in the nation’s largest automotive retailer.

Bill Gates -- No. 2 on Forbes magazine’s 2010 ranking of billionaires -- already holds about 15 percent of AutoNation Inc. in his foundation and investment company. Last week, AutoNation’s board gave the Microsoft founder the right to purchase more stock subject to certain conditions.

The move, detailed in filings to the Securities and Exchange Commission, doesn’t reveal the billionaire’s actual intentions about buying more AutoNation stock. But it was made to comply with a law that requires “major” stockholders, or those holding 15 percent of shares or more, to seek certain board approvals before increasing their stakes.