Why Exelixis, Inc., Plug Power Inc., and King Digital Entertainment PLC Are Today's 3 Worst Stocks

A down day for the markets couldn't stop three of today's big losers. The S&P 500 took a beating late in the day following renewed concerns over European and American sanctions against Russia. The index dropped 0.7% after a fine start to the day, knocking out all the earlier gains that had come behind a surprising 2.2% rise in durable goods orders for the month of February. Russia's ongoing territorial standoff with Europe shouldn't shake the foundation of your portfolio, but it's worth keeping an eye on: Expect more volatility in the days and weeks ahead as the situation develops and the market digests the impact on Europe, particularly surrounding natural gas and energy.

Around the market, however, three big losers didn't need Russia's help to take a beating on the day. Biotech stock Exelixis took the title of today's hardest-hit loser, plunging by a migraine-inducing 39.4%, while investors hammered fuel cell producer Plug Power to the tune of a 24% drop. The most notable loser of the day, however, came from the market's newest stock, as shares of new IPO King Digital Entertainment lit the market on fire in all the wrong ways today in its debut, plunging by 15.5%. Let's catch on up on the details.

A tough day for Exelixis investors
Exelixis investors have plenty to be happy about with this stock's rise over the past year, but everything fell apart today. The biotech stock's apocalyptic fall-off came after the relatively harmless announcement that the company's clinical trial of cancer therapy cabozantinib's use in treating prostate cancer will continue beyond its interim point. Sharesholders turned to fury over the announcement, as many had expected the trial to end early.

Source: Exelixis Media Resources

Why the precipitous plunge? As JPMorgan analyst Cory Kasimov told Bloomberg, several other major prostate cancer drugs in late-stage trials had ended early, making Exelixis' continuation a downbeat result. Still, investors shouldn't panic in the wake of today's bloodbath. Cabozantinib's already scored one approval -- albeit a minor one -- from the FDA back in 2012 and received European regulatory approval for metastatic medullary thyroid carcinoma, or MTC, in certain patients just this week. That's not going to shake up the company's revenue stream much, but if cabozantinib can win over regulators in treating prostate cancer, analysts project that the drug could emerge as a blockbuster with more than $1.6 billion in annual sales. That's driven much of the excitement over Exelixis through the past year, and considering that cabozantinib's still in trials for other cancer indications as well, it's worth staying patient with this biotech pick after the big sell-off and waiting to see how the drug performs in the near future.

Plug Power might not have suffered the same drop as Exelixis, but the stock's 24% decline wasn't any less painful to investors. The company had delighted the market yesterday after the firm's CEO Andy Marsh announced that Plug Power had signed a sizable deal with a worldwide automaker. Great news -- until investors found out that it was the exact same deal that Marsh had spoken about nearly two weeks earlier in the wake of the company's earnings. More of a misunderstanding and a disappointment than any drastic problem, Plug's drop today shouldn't shake your opinion of the stock too much. Plug Power's already in line to supply fuel cells to forklifts in warehouses, but the volatility around shares of the company invites caution.

Still, neither Plug Power's drop nor Exelixis's plunge made as much news around the market as the IPO of Candy Crush Saga developer King Digital. Suffice to say, King's first foray as a publicly traded company did not quite go as the firm had planned with the big drop-off from the stock's IPO price of $22.50. King's trying to harness the power of social and mobile gaming following the rise of the mobile industry, and it's betting heavily on portfolio mainstay Candy Crush Saga, a game that dominates among King's reported 144 million daily users.

That user base has helped drive King's recent financial surge, as the company reported more than $600 million in sales in its most recent quarter. However, with Candy Crush such a dominant piece of King's architecture, it's questionable whether or not the company will be able to repeat its success in creating multiple smash hits to drive user growth -- or whether it can retain and grow Candy Crush's small minority of paying customers in the future. For now, it wouldn't be a surprise to see more turbulence from this young stock.

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The article Why Exelixis, Inc., Plug Power Inc., and King Digital Entertainment PLC Are Today's 3 Worst Stocks originally appeared on Fool.com.

Dan Carroll has no position in any stocks mentioned. The Motley Fool recommends and owns shares of Exelixis. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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