Market says Microsoft is most valuable

The software giant's market capitalization, a measure of the total value of a company as judged by the stock market, has reached $265.1 billion based on Monday's closing stock price of $49.29, making it the world's most valuable company.

Microsoft passed General Electric to get the top spot, but was helped out by a steep decline in GE's stock price over the last few months. GE had a market cap of $242.3 billion at Monday's closing bell.

The victory, however, is somewhat hollow. The market capitalizations of both Microsoft and GE have been more than halved since their market peaks. The antitrust trial hurt Microsoft's market cap, and concerns about future growth has hampered GE.

Microsoft has been in and out of the top spot over the years. GE passed it last year in a ranking produced by the Financial Times.

Microsoft, which reports fiscal first-quarter earnings on Thursday, is the only tech company to make it into the top 10. Retailer Wal-Mart is third, with a market cap of $239.5 billion, followed by Exxon Mobil at $236 billion, and Pfizer at $191.4 billion.

The rankings are fluid and subject to the whims of the market. In 2000, Cisco Systems was the most valuable company with a market cap topping $500 billion. GE regained the crown as the telecom meltdown hurt Cisco, whose market cap was $72.3 billion as of market close Monday.