Apple overtakes Microsoft, is now No. 2

Measured by market capitalization, it is second only to Exxon Mobil among U.S. companies

At the close of market Wednesday, Apple's (aapl) share price stood at $244.11, down $1.11 (0.45%) for the day. Microsoft (msft), on the other hand, closed at $25.01, down $1.06 (4.07%).

Why is this significant? Because Apple's market capitalization ($221.36 billion) just overtook Microsoft's ($219.35) for the first time in 20 years, making it the second most valuable company in America, after Exxon Mobil (xom).

Market cap -- the product of a company's share price and the number of outstanding shares -- is a somewhat arbitrary measure. But in this case it does reflect the two company's shifting positions in the market.

Apple's share price has climbed nearly 520% over the past five years. Microsoft's is up 9.5%.

See also:

[Follow Philip Elmer-DeWitt on Twitter @philiped]

All products and services featured are based solely on editorial selection. FORTUNE may receive compensation for some links to products and services on this website.

Quotes delayed at least 15 minutes. Market data provided by Interactive Data. ETF and Mutual Fund data provided by Morningstar, Inc. Dow Jones Terms & Conditions: S&P Index data is the property of Chicago Mercantile Exchange Inc. and its licensors. All rights reserved. Terms & Conditions. Powered and implemented by Interactive Data Managed Solutions