WASHINGTON –- Billionaire investor George Soros more than doubled his stake in Microsoft Corp.'s common stock to 415,500 shares as of March 31 as sales of the company's Windows Vista software exceeded expectations.

Soros previously reportedly owned 198,100 shares in December.

News sources also stated that Soros reported in a filing with the U.S. Securities and Exchange Commission that he had also taken a stake in the call options of Microsoft with 684,000 shares worth about $19.06 million as of March 31.

Last month, Microsoft said Vista sales helped the unit that sells Windows for personal computers exceed revenue forecasts by as much as $400 million.

At the same time that Soros was increasing his stake in Microsoft, he dropped his stakes in eBat and Take-Two, in which he had previously reportedly held 101,745 shares and 1.01 million shares, respectively, as of Dec. 31.

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News sources further reported that Soros also cut his stake in Oracle to 99,000 shares from 808,000 shares; Goodyear Tire & Rubber Co., in which he'd previously held 1.07 million shares; and Diamond Offshore Drilling Inc., in which he'd held 814,100 shares as of Dec. 31.

One news source observed that a "notable trend" in Soros' portfolio was the acquisition of relatively small stakes in dozens of retailers and consumer companies, which of which are mainstays at malls throughout the U.S.

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