Shares of Amazon.com (NASDAQ:AMZN) slipped in after-hours trading on Thursday, falling about 2.5% as of 5 p.m. EDT. The pullback in the stock price came after the company announced second-quarter results that missed analyst estimates on several key metrics. But there was one important silver lining in the update: The e-commerce and cloud-computing giant's revenue growth rate accelerated -- a change of pace from a trend of decelerating growth in recent quarters.

Here's a look at the results.

Boxes in an Amazon fulfillment center

Image source: Amazon.com.

Top- and bottom-line performance

Amazon's revenue rose 20% year over year -- an acceleration from 17% growth in the first quarter. This puts Amazon's revenue growth rate back in line with growth seen in the company's fourth quarter of 2018. Revenue for the period was $63.4 billion -- at the high end of management's guidance for revenue during the period to be between $59.5 billion and $63.5 billion. In addition, the top-line figure was ahead of analysts' average forecast of revenue of $62.5 billion. 

Helping drive this growth was 37% year-over-year growth in Amazon Web Services (AWS) revenue and an acceleration in the company's online stores revenue. Online stores revenue rose 16% year over year to $31 billion. This is up from 12% growth in the first quarter of 2019.

Management credited the acceleration in online sales growth to the company's rollout of free one-day delivery. "Customers are responding to Prime's move to one-day delivery -- we've received a lot of positive feedback and seen accelerating sales growth," said Amazon CEO Jeff Bezos in the company's second-quarter earnings release. "Free one-day delivery is now available to Prime members on more than ten million items, and we're just getting started."

Third-party-seller services revenue also accelerated, rising 25% year over year -- up from 20% growth in Q1.

Meanwhile, Amazon's earnings per share rose from $5.07 in the year-ago quarter to $5.22. This metric fell short of analysts' average forecast of earnings per share of $5.57. The worse-than-expected profitability is likely because Amazon's high-margin AWS business grew slower than analysts were expecting.

Slowing growth in the cloud

Amazon's cloud-computing AWS business remains a key part of the company's consolidated performance. Though Amazon's first-quarter AWS revenue of $8.4 billion represented just 13% of total revenue, the segment boasts an impressive 25% operating margin. In addition, the segment is growing much faster than Amazon's e-commerce business.

Given its importance to Amazon's business, it's of note that AWS revenue growth has been decelerating meaningfully over the last few quarters. The segment's 37% constant-currency revenue growth in Q2 was down from 42% growth in the first quarter of 2019 and 46% growth in the fourth quarter of 2018.

The degree of this deceleration has taken analysts by surprise. On average, analysts expected AWS revenue to rise 39% year over year to $8.5 billion.