Amazon just reported profits of $239 million, or 51 cents per share on revenue of $25.59 billion, results that came in below what Wall Street expected. Analysts on average were expecting Amazon to earn 66 cents a share on $26.06 billion, a mismatch that sent shares down in after-hours trading.

For its current quarter, Amazon says it expects to bring in net sales between $18.2 and $19.9 billion. That's near the higher end of the $19.67 billion Wall Street expected, but comes with what Amazon warns could be a range between a $200 million gain or loss in either direction.

Despite the positive sales growth, investors were disappointed by the results. Shares of Amazon's stock were trading down as much as $40.51 after-hours, sliding more than 10 percent. Though in the run-up to earnings, the stock hit new all-time highs, rising above $400 per share.

The story is a familiar one for Amazon, which has posted slim profits and sometimes millions in losses in the name of future growth. While sales have grown, so too have the company's expenses as it spends on new ventures including shipping infrastructure and content deals that could set it apart from rivals.

Much of the company's boasting has instead turned to sales, which have come in higher than what Wall Street's expected. Amazon CEO Jeff Bezos gave a small preview on this just-reported quarter last month, boasting that it was the "best ever" holiday sales period the company's ever had, including an all-time record for Cyber Monday sales. Bezos also said that the company had to limit the number of people signing up for its Prime subscription service to keep it from affecting the quality of service for its existing members. In the company's press release announcing the earnings, Bezos said the company was "just scratching the surface of what world-class customer service can be."

Media deals and other investments

During the quarter Amazon launched, expanded, and invested in numerous products and projects. On the product side that list included software updates to the second-generation model of its Kindle Paperwhite and new HDX models of its Kindle Fire tablet line, along with Kindle Matchbook, a service that gives physical book buyers digital copies on some titles. Investments include hiring 70,000 seasonal employees to ship out holiday orders, acquiring educational company TenMarks, announcing plans to open up six new fulfillment centers, and inking content deals with PBS and A24 films.

For the entire fiscal year, Amazon's sales were up 22 percent from 2012, a figure the company says was slightly higher at 24 percent when excluding changes to foreign exchange rates. Amazon's operating income also increased by 10 percent to $745 million.

Update: Amazon announced plans to possibly increase the price of its Amazon Prime subscription service by $20 to $40 a year in the US, citing the increased price of shipping. No word yet on the exact amount, or the timing for when the changes to the $79 a year program will go into effect.