Amazon shares plunge as record profit still misses estimates

Amazon.com Inc posted its most profitable quarter ever on Thursday but the world's No. 1 online retailer still managed to disappoint Wall Street by badly missing estimates, sending its shares down more than 13 percent in after-hours trading.

The results, as well as the company's determination to invest more in new areas and its extremely low profit margins, brought back perennial questions for investors about the company's ability to consistently earn money.

"By comparative retail standards, Amazon's level of profitability is still painfully weak," said Neil Saunders, head of retail analyst firm Conlumino, who is still positive on Amazon's prospects. "For every dollar the company takes, it makes just 0.75 of a cent in profit."