2019 was one of the rare years in which Alphabet (NASDAQ:GOOG) (NASDAQ:GOOGL) stock underperformed the S&P 500, albeit just slightly. The tech giant's share price rose 28.2% while the S&P 500 climbed 28.9%. With the company's fourth-quarter earnings report scheduled to be released after the market close on Feb. 3, investors will soon get to see whether or not the online search giant has been delivering the sort of results that could help its stock return to outperforming the market in 2020.

Of course, it's not like 2019 was a bad year for Alphabet. Total revenue for the first three quarters jumped 19% year over year. Further, income from operations rose by an even stronger 29% to $25 billion over the same time frame. 

But when Alphabet reports, investors will want to pay particular attention to two key areas: the company's top-line momentum and the growth trajectory of its thriving "Google other" segment.

A search bar field for inputting online searches.

Image source: Getty Images.

Revenue growth

Alphabet's revenue rose impressively in the third quarter -- 22% year over year in constant currency. That was in line with its 22% constant-currency revenue growth in Q2, and an acceleration from the 19% growth in Q1. Mobile search, YouTube, and the company's cloud computing services were key drivers of the Q3 gain, consistent with trends from prior quarters.

For Q4, analysts expect Alphabet to report revenue of $46.9 billion, up 19.5% year over year. But there are factors that could lead to a top-line figure that's meaningfully different. As Alphabet CFO Ruth Porat said in the company's third-quarter earnings call, there is "variability in year-on-year revenue growth rates from quarter-to-quarter [for our advertising business] as we've often discussed."

Explaining further, she noted:

[W]e manage our business for the long term and not on a quarterly basis, and we remain very focused on continuing to enhance the experience for users and advertisers over the long term.

Google other

Alphabet's "Google other" segment, which is primarily made up of its cloud business, the Google Play app store, and its hardware offerings, has been a key revenue driver for the company: The segment's revenue increased 39% year over year to $6.4 billion during Q3.

It's an important component for investors to keep an eye on, as it includes a diverse set of businesses that don't fall into the advertising category -- and it's growing fast than that core business.

If the tech company scores well in these two areas (total revenue growth and Google other) it will likely give investors confidence in the company's momentum and its prospects for further strong growth.