Investors showed their enthusiasm for Costco's (COST -2.56%) business by sending shares up over 40% in 2019 as the warehouse retailer notched impressive market share wins. That leading sales growth came with robust profit growth, too, thanks to an expanding pool of subscribers who are paying higher average annual membership fees.

Expectations are for these positive trends to carry through into Costco's fiscal second-quarter results, which are due out after the market closes on March 5. Below, we'll look at a few key metrics to watch for in that report.

A man shops in a warehouse retailing store.

Image source: Getty Images.

Customer traffic

Investors have every reason to expect to see solid sales growth for the full quarterly period, given that Costco revealed strong monthly sales data in both January and February. The December shopping month saw a 9% spike, in fact, after accounting for calendar shifts. Its January sales month was nearly as good, although comps slowed slightly.

Costco will reveal its customer traffic change for the fiscal second quarter, and that metric will help indicate whether it is still soaking up market share in the retailing industry. Both Walmart and Target announced slowing growth here but the warehouse giant might have bucked that trend by achieving traffic growth of around 3% or more.

Subscriber trends

Costco makes more money from its subscription fees than its product markups, which makes membership metrics a natural focus for investors. Subscriber renewal rates have been trending higher into record territory lately, reaching 90.9% last quarter. Another uptick this week would confirm that the retailing chain is providing plenty of value for its shoppers. It would also likely combine with a growing base, plus increased demand for higher-tier membership levels, to push fee income higher.

Subscription fee income rose 6.1% last quarter to outpace Costco's 5.6% reported sales gain. Investors are looking for a similar boost in profitability this quarter as the consumer staples retailer's earnings rise to $2.07 per share from $2.01 per share a year ago.

The spending outlook

Management's latest prediction called for capital spending to land at $3 billion for the fiscal year 2020, with the bulk of those investments set to occur in the second half of the year. That forecast includes outlays for an expanding global store base, plus e-commerce growth initiatives aimed at bringing home delivery for both non-perishable and grocery products to most of the U.S.

Its retailing peers, including Walmart and Home Depot have said in recent weeks that they plan to continue an elevated spending level at least through 2020 as they work to make their businesses more convenient for omni-channel shopping. Those pressures reduced operating income margin last year and should pressure profitability in 2020.

Costco might have similar comments about its own spending plans this week, especially since it is trying to build a national delivery network from a smaller base of stores. But investors will be happy to accept that temporary boost in cash outflow, especially if the retailer continues to steal market share from most of its national retailing rivals.