Amazon.com (NASDAQ:AMZN) is slated to report its fourth-quarter and full-year 2019 results after the market closes on Thursday, Jan. 30. This is a particularly important report, as it includes the holiday period.

Investors will probably be approaching the report with uncertainty. In both the second and third quarters, the e-commerce behemoth beat Wall Street's consensus revenue estimate but missed on the bottom line. The second quarter's earnings miss broke a five-quarter string of expectation-demolishing results, and the third-quarter's earnings results marked the first time in about two years that Amazon's quarterly earnings have declined year over year.

Against this backdrop, it's perhaps not surprising that Amazon stock underperformed the market last year, gaining 23%, compared with the S&P 500's 31.5% return. In 2020, shares are up 0.9% through Jan. 17, trailing the broader market's 3.1% return. Of course, the stock remains one of the best performers in both the tech and consumer goods sectors over the long term.

Here's what to watch when Amazon reports.

Packages moving on a conveyor belt in an Amazon fulfillment center, ehchages comk

Image source: Amazon.com.

Key quarterly numbers

Metric Q4 2018 Result Amazon's Q4 2019 Guidance Amazon's Projected Change (YOY) Wall Street's Q4 2019 Consensus Estimate Wall Street's Projected Change (YOY)

Revenue

$72.38 billion

$80.0 billion to $86.5 billion

10.5% to 19.5%

$85.89 billion

18.7%

Adjusted earnings per share (EPS)

$6.04

N/A

N/A

$4.04

(33.1%)

Data sources: Amazon.com and Yahoo! Finance. YOY = year over year. Wall Street estimates as of Jan. 17. Note: Amazon does not provide earnings guidance. 

For the fourth quarter, Amazon expects operating income in the range of $1.2 billion to $2.9 billion, representing a decline of 24% to 68% from the year-ago period. The reason for the projected drop is the company's plan to continue spending on upgrading Amazon Prime's core free delivery benefit from two days to one day. This huge project, started in early 2019, is naturally negatively effecting the company's current profits, though it is having the desired effect of increasing revenue. Over the long term, the company believes this upgrade will spur growth on the bottom line as well as on the top.

The Prime delivery upgrade's effects on revenue growth and the project's status 

While it's still relatively early, investors can probably expect that the Prime delivery upgrade is continuing to boost revenue growth in the company's North America segment.

Hopefully, CFO Brian Olsavsky will give an update on the earnings call on the status of this project. It would be good news to hear that the heavy spending is mostly behind the company.

Amazon Web Services' overall growth

As always, investors should focus on AWS's overall growth, because this segment drives the company's overall profits. Not only is the cloud-computing service extremely profitable, but it's also growing fast.

That said, AWS's operating income growth has been decelerating. In Q3, the segment's revenue grew 35%, but operating income grew only 9%, resulting in an operating margin of 25.1%. This metric is down from 25.2% in the second quarter, 28.9% in the first quarter, and 29.3% in the fourth quarter of 2018

Q1 2020 guidance

As is usually the case, Amazon's guidance for the next quarter, Q1 2020, will probably be the bigger factor in the market's reaction to its report than its current results. (The company provides an outlook for revenue and operating income but not for earnings. However, the operating income guidance gives investors a decent idea as to what year-over-year percentage change the company expects on the bottom line.)

So you should know Wall Street's Q1 2020 expectations: Analysts expect revenue to increase 20% year over year to $71.65 billion and adjusted earnings per share to decline 9.2% to $6.44.