Shares of online marketplace eBay (EBAY 0.48%) were slammed in 2018, falling 25% during the year. Decelerating gross merchandise growth and a sell-off in the stock market during the fourth quarter of 2018 that hit tech stocks particularly hard have weighed on the stock.

While these have been unfortunate times for eBay shareholders, it means the bar is lower going into the company's upcoming fourth-quarter earnings report. eBay is scheduled to report its quarterly results on Jan. 29. Can eBay excite investors again?

Here are three key metrics eBay investors will want to watch when the online marketplace company reports its fourth-quarter results in a couple of weeks.

eBay offices in San Jose, California

Image source: eBay.

Active buyer growth

In the first quarter of 2018, eBay's year-over-year growth in active buyers on its platform dipped below 5% for the first time since the fourth quarter of 2016 -- and the key metric hasn't rebounded. For eBay's first, second, and third quarter of 2018, active buyers increased 4% year over year.

While management has admitted it's not eBay's aspiration for active buyer growth to remain at 4%, management also doesn't seem optimistic that active buyer growth will reaccelerate in its fourth quarter. Investors, however, should look for eBay to at least maintain its 4% year-over-year growth rate for active buyers during the quarter.

Revenue growth

eBay's revenue growth story hasn't been a positive one recently. Management initially guided for full-year 2018 revenue to increase 7% to 9% year over year when adjusted for currency changes. But a deceleration in the company's quarterly year-over-year revenue growth rates recently caused management to reduce its outlook for the year. eBay now expects full-year currency neutral revenue to rise 6%

For eBay's fourth quarter, management guided for organic currency-neutral revenue growth of 4% to 5%. That would be a deceleration from eBay's 6% currency-neutral revenue growth in its third quarter.

Share repurchases

With eBay stock tumbling 15% during its fourth quarter, it will be interesting to see whether the company ramped up the amount of money it spends repurchasing its shares. eBay is in a position to take advantage of the stock's pullback and buy shares aggressively. The company ended its third quarter with $9 billion in cash, cash equivalents, and non-equity investments. In addition, the company had $4.7 billion remaining in its share-repurchase authorization. 

In eBay's third quarter, the company spent $1 billion repurchasing its stock, in line with what it has spent buying back shares in recent quarters. Will eBay finally spend more money purchasing its stock since shares are trading lower?

eBay is scheduled to report its fourth-quarter results after the market closes on Tuesday, Jan. 29.

Check out the latest eBay earnings call transcript.