Amazon mania: Stock hits all-time high

As Amazon gets ready for its press event today, investors rush into the stock in anticipation of hearing something big.

Charles Cooper Former Executive Editor / News
Charles Cooper was an executive editor at CNET News. He has covered technology and business for more than 25 years, working at CBSNews.com, the Associated Press, Computer & Software News, Computer Shopper, PC Week, and ZDNet.
Charles Cooper

Shares of Amazon reached an all-time high Thursday as investors bid up the stock in anticipation of the company's announcement of additions to its Kindle tablet line (CNET's live blog of the event starts at 10 a.m.). Amazon's stock is up more than 43 percent for the year. In part, the stock is climbing on the assumption that gross profit margins are going to continue to increase. During Amazon's second quarter, gross profits margins widened to 26.1 percent from 24.1 percent, which surpassed Wall Street's expectations for the company. At least for now, that calmed the critics who pointed to the continuing heavy investments in marketing, infrastructure, and fulfillment.

To the critics, Amazon's amazing stock run continues to bewilder. they point to several metrics -- including a price/book ratio of 14.77 and a price/sales ratio of 2.04, both of which are relatively high -- as evidence that investors are, well, more than irrationally exuberant. But while the numbers say one thing, the market continues to like Amazon's story and keeps bidding up its shares.

In early afternoon trading, Amazon's stock was up more than 2 precent to $251.26.