It’s another sign of the times in the early 21st century when Apple’s stock market value eclipses that of retail giant Walmart. Philip Elmer-DeWitt in Fortune:

Ninety minutes after Apple (AAPL) opened its online store for iPad pre-orders Friday morning, a burst of trading — roughly 2 million shares in 30 minutes — pushed its stock price to $227.73 and its market cap to $206.5 billion.

Values go up and down, but Apple is the third most valuable company in the US, slightly higher than Walmart and Berkshire Hathaway. As a comparison, note that Apple’s annual revenue is approximately $50-billion, while Walmart exceeds $400-billion.