Strong sales growth and the popularity of its Amazon Prime offering helped send Amazon.com (NASDAQ: AMZN) earnings more than 250% higher on a year-over-year basis. In its second quarter, the online retailer founded by Jeff Bezos in 1994 posted net income of $78 million, or 19 cents per share. Revenue was 35% higher at $2.89 billion, up from $2.14 billion in the year-ago period. According to the latest estimates reported by Thomson First Call, analysts were expecting earnings per share of 16 cents from Amazon on revenue of $2.81 billion.

According to the company's press release, North American sales grew by 38% in the latest quarter, while International sales were up 31%. Mr. Bezos noted in the release that the firm's "strong revenue growth ... was fueled by low prices and the added convenience of Amazon Prime," a feature that provides unlimited two-day shipping for an annual fee of $79.

Looking ahead to the third quarter, Amazon officials expect net sales to grow between 30% and 38% on a year-over-year basis, hitting between $3.0 billion and $3.175 billion for the period. Operating income is expected between $75 million and $110 million, a growth rate of between 88% and 175% compared with the previous year's third-quarter reporting period.

For the full year, Amazon expects to grow net sales to between $13.8 billion and $14.3 billion, with operating income targeted in a range between $540 million and $640 million.

So far, it looks like a repeat performance of the spring earnings period could be in the cards for Amazon. Despite today's dismal performance in the overall market, Amazon shares are charging higher in after-hours activity and are currently up 8%.

Beth Gaston Moon is an analyst at Schaeffer's Investment Research.