The past year has been a busy one for shareholders of eBay (EBAY 0.58%). The online marketplace's growth rebound fizzled in 2019, with sales falling under the weight of intense competition and added sales taxes in the core U.S. market. Yet investors received some good news, too, mainly in the form of eBay's $4 billion divestment of its StubHub ticket business.

Through all of that, the stock barely kept pace with a booming market last year despite having been up by nearly 50% at one point in 2019. Yet eBay has a prime chance to improve on that narrative when it announces holiday-season sales results in just a few days.

Let's look at three metrics worth following when eBay reports fourth-quarter earnings on Tuesday, Jan. 28, after the market close.

A woman shops online through her smartphone.

Image source: Getty Images.

1. Growth trends

Most investors who follow the stock are expecting eBay to post a 2% sales decline on Tuesday. But that reported revenue figure has a lot of noise in it from currency exchange movements, given the company's substantial international business.

For a clearer picture of demand trends, follow eBay's buyer pool, which has been growing at a steady 4% clip for more than a year. Gains in that area have become increasingly important given the marketplace's worsening sales volume trends. Its volume has declined by 5% or more in the U.S. market in each of the last three quarters, in fact, and it is expected to continue being pressured by the higher sales taxes that are raising prices for buyers. eBay's international growth has slowed for four consecutive quarters, too, reaching just 1% in the third quarter.

These mostly weak trends will put pressure on interim CEO Scott Schenkel and his team to show some progress that ideally improves on last quarter's 3% slump in global marketplace revenue.

2. Prime cash flow

eBay's asset-light sales model has always been much more profitable than the ones relied on by more integrated retailers like and Walmart, which maintain their own vast inventory and fulfillment operations. That profitability gap has only increased recently, thanks in part to eBay's higher fees. The transaction fee that it charges buyers rose to 9.7% last quarter, up from 8.8% in mid-2018.

Continued success here should show up in two important metrics: operating margin and cash flow. On the margin front, look for the tech stock's operating margin to improve for the second straight quarter, rising to 28% of sales from 27% in Q3. Free cash flow should land at around $2.3 billion for the year, equating to 21% of eBay's annual sales haul.

3. Looking ahead

Investors will get to see a detailed financial outlook when eBay posts its 2020 forecast on Tuesday. Assuming it achieves management's 2019 prediction, the company will have the chance to target a rebound after growth slowed to 2% from 5% in 2018. Another sluggish outlook, on the other hand, will add even more pressure on executives to discuss how eBay plans to stem its market share slide.

The company will likely highlight the soaring direct capital returns that will be supported by its StubHub sale. But investors won't be in a celebratory mood until they see a clear path back toward faster marketplace growth, especially given the booming e-commerce industry.