The stock market went through a topsy-turvy day Wednesday, as optimism about a potential resolution to the Ukrainian situation trumped nervousness over how the Federal Reserve might address certain risks that Chairwoman Janet Yellen brought up in Congressional testimony today. Even though the broader major-market indexes closed higher, Groupon (NASDAQ:GRPN), Zulily (NASDAQ: ZU), and Whole Foods Market (NASDAQ:WFM) plunged today.

Source: Groupon.

Groupon plummeted almost 21% even after the daily deals-turned-online retail company issued reasonably strong quarterly results. Groupon posted a narrower adjusted loss than investors had expected, and revenue climbed 26%. But investors still seem unconvinced that the company's long-term online retail strategy will prove successful, especially as it ventures into territory in which far larger players already hold dominant positions. Until Groupon shows much better results than it gave investors today, it'll be hard for the company to convince shareholders that its turnaround is for real.

The nearly 30% collapse in Zulily shares came amid rising losses and operational concerns about the online retailer's just-in-time approach to fulfilling orders. Sales at Zulily soared by 87%, which was better even than the ambitious growth expectations that investors already had for the stock. Even though Zulily raised its full-year sales guidance, earnings didn't make the grade, as a rush of orders as Easter approached forced the company to incur additional costs and suffer longer shipping times. The challenge that Zulily will face is reassuring customers that any negative experiences they might have had won't be repeated, as online retail is so fickle that Zulily can't count on getting many second chances.

Whole Foods Market suffered a 19% loss as the premium grocer's quarterly results fell short of expectations. Same-store sales growth of 4.5%, overall revenue gains of nearly 10%, and roughly flat net income year-over-year weren't up to par, and Whole Foods also cut its guidance for revenue growth by one-half to one percentage point and for earnings per share by $0.06 to $0.09 per share. Many investors are nervous that Whole Foods will dilute its margins by offering its high-quality food at lower prices in order to compete with other grocers, which increasingly are jumping onto the organic and natural-foods bandwagon. Yet in the long run, Whole Foods still expects to expand its network of stores and find new ways to use the loyalty of its customer base to bring sustainable growth.

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