Microsoft's Market Value Drops $80B

NEW YORK (AP) - Microsoft's dramatic plunge Monday shaved more than $80 billion from its market value.

That knocked Microsoft's market capitalization from roughly $552.9 billion on Friday to $472.5 billion. Co-founder Bill Gates, who holds more than 785 million Microsoft shares, lost about $12.1 billion in the rout.

Market capitalization is determined by multiplying the number of shares outstanding by the current stock price. Last week, Microsoft jostled with Cisco Systems Inc. (NasdaqNM:CSCO - news) for the top ranking, but Monday's technology selloff sent Microsoft into third place behind General Electric Co. and Cisco.

Microsoft, along with chip maker Intel Corp. (NasdaqNM:INTC - news), is included in both the Nasdaq composite index and the Dow Jones industrial average. Because the Nasdaq is a weighted index that gives more significance to its largest companies, Microsoft's slide dragged the index to its worst performance in history - a 349.15-point plunge.

By contrast, the Dow gives equal weight to each of its 30 components. It rose 300 points on Monday as financial, retail and drug stocks soared, wiping out Microsoft's losses.