There's never a shortage of stocks going the wrong way in any given chunk of time. No stock goes straight up, and sometimes fundamentals can get a bit wobbly. Let's take a closer look at five of this past week's biggest sinkers.


May 9

Weekly Loss

Roundy's (NYSE: RNDY)



Whole Foods Market (NASDAQ:WFM)



Ballard Power Systems (NASDAQ:BLDP)



FuelCell Energy (NASDAQ:FCEL)






Source: Barron's.

Let's start with Roundy's. The Midwestern grocer became a "clean up, aisle four" situation after delivering uninspiring financials. The supermarket chain's adjusted profit of $0.01 a share was well below the $0.19 it posted a year ago and the $0.03 Wall Street pros were expecting. Roundy's is in the process of expanding one of its concepts through Chicago as it clears out of Minneapolis by unloading another concept. All of the moving parts and the weak profitability were enough to lead Bank of America's retail analyst to downgrade the stock.

Whole Foods Market has been a steady winner over the years, but the stock got rocked last week after slashing its outlook again. The leading organic grocery-store chain is now expecting revenue to climb 10.5% to 11% this year. This is the third time it whittled down its guidance. It initiated its forecast for 2014 several months ago by pegging top-line growth to clock in between 12% and 14%. 

It's been a wild ride for fuel-cell stocks, and we saw Ballard Power and FuelCell Energy shed 19% and 15% of their value, respectively, this past week. There was no particular newsy nugget to account for the niche's slide this week. It was just more negative momentum from the prior week, when Ballard Power missed Wall Street's revenue target in its latest quarter. It also didn't help that ClearEdge Power, a California-based fuel-cell maker, filed for Chapter 11 earlier this month.

How well investors have fared in fuel-cell stocks depends on when they hopped on. FuelCell Energy has shed a brutal 60% of its value since peaking two months ago, but the stock is still trading 35% higher so far in 2014. If you think that's volatile, Ballard Power's swings have been even wilder. It has plunged 66% since topping out in March, but it's actually still brandishing a 90% year-to-date gain.

Groupon also became more of a deal for investors after posting quarterly results. The dagger here was in the daily-deals leader's guidance. Groupon's outlook for the current quarter calls for $725 million to $775 million in revenue for the current quarter. Eyeing the midpoint of that range would translate into a year-over-year decline on the top line and less than what Wall Street was forecasting. Several analysts, including Northland Securities, Goldman Sachs, Wunderlich, and Evercore Partners slashed their price targets on Groupon after the report.

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