Stocks gave up significant ground last week, with both the Dow Jones Industrial Average (DJINDICES:^DJI) and the S&P 500 (SNPINDEX:^GSPC) shedding more than 2%. The drop left the Dow in negative territory so far for the year while the broader S&P 500 is now up by less than 1%.

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Earnings season marches on, with dozens of companies set to announce quarterly results over the next few days. Costco (NASDAQ:COST) and Target (NYSE:TGT) stocks could make big moves in response to their holiday quarter numbers. Meanwhile, Vail Resorts (NYSE:MTN) will issue an important update on its peak ski season demand.

Here are a few things to look for in these upcoming reports.

Costco's renewal rate

Costco posts its fiscal second-quarter earnings numbers after the market closes on Wednesday. The warehouse retailer is coming off a strong start to its fiscal 2018 that included spiking customer traffic and a hefty profit bump driven by an increase in its annual membership fee. Costco fared well in its e-commerce sales channel over the holiday season, too, as digital revenue jumped 40% to $1.3 billion.

A customer browses a warehouse store.

Image source: Getty Images.

Investors this week will be watching for signs that this growth momentum is holding up in both the e-commerce segment and in Costco's physical stores. At the same time, look for management to spend time talking about the membership renewal rate. They had predicted this key loyalty metric would begin climbing back toward the record 91% rate the retailer set in 2015, but instead the rate held steady in the fiscal first quarter. A weak result on Wednesday might imply market-share losses, likely to e-commerce giants.

Target's customer traffic

Investors already know a few tantalizing details about Target's holiday-season results. The retailer revealed in early January that comparable-store sales shot up to a 3.4% pace during the key months of November and December. That boost marked an acceleration over the prior quarter's 0.9% uptick. It also blew past management's forecast of between 0% and 2% higher comps.

On Tuesday, we'll find out just how much of that growth came from the digital sales channel, and how much of it was due to increased customer traffic at stores. That's an important metric to watch since the sales mix will determine whether Target's profitability continues trending lower. Ideally, the company could achieve positive comps in the context of rising gross margin, but that hasn't occurred over the last few quarters.

Still, comps are on pace to rise by about 1% in 2017 after having dipped by roughly the same amount in the prior year. Target's updated 2018 outlook will determine whether the retailer believes it can continue that modest sales acceleration into a second year.

Vail Resorts' ski visits

Vail Resorts will announce its fiscal second-quarter results on Thursday morning, and investors are eager to hear just how challenging the peak ski season has been in its North American geography. Back in December, management noted that key metrics, including season pass volume and pricing, pointed to a solid season ahead. However, snowfall levels were dramatically below average across several of its core properties in December and November, executives warned in mid-January. As a result, Vail lowered its sales and profit guidance.

A skier looks out over a mountain.

Image source: Getty Images.

Management hinted at improving conditions on the way, but there's no guarantee these were helpful enough to avoid a double-digit decline in North American resort skier visits.

Vail Resorts can't control the weather, but the company's surest way to boost returns over time is by improving the guest experience. Thus, look for the management team to discuss their plans to pour cash into upgrading lifts in the Whistler Blackcomb and Vail properties in preparation for modest summer traffic, followed by a 2018 peak ski season that's closer to normal.

Demitrios Kalogeropoulos owns shares of Costco Wholesale. The Motley Fool recommends Costco Wholesale and Vail Resorts. The Motley Fool has a disclosure policy.