Why Geron, Express, and Herbalife Tumbled Today

The stock market demonstrated its continuing confusion Wednesday, initially falling sharply on ongoing concerns about tension in the Crimea and Chinese economic sluggishness. Yet by the end of the day, the S&P 500 had actually managed to post a gain on the day, once again showing the resiliency of the five-year-old bull market. Unfortunately, though, shareholders in several stocks still suffered substantial losses, with Geron , Express , and Herbalife among the market's losers today.

Geron plunged 62% after the biotech company got bad news about its key imetelstat drug, as the FDA issued a clinical hold on the treatment for multiple myeloma and essential thrombocythemia. The FDA cited risks of liver damage and abnormal liver-function test results in Geron's phase 2 study, and because of the hold, Geron probably won't be able to start a scheduled myelofibrosis study for imetelstat as soon as it had hoped. With Geron still striving to find a viable long-term business model after having given up on the stem-cell research it had done in the past, any threat to imetelstat's success has severe implications for the company's survival -- as shareholders discovered today.

Express fell 12% as the retailer reported poor financial results and gave discouraging guidance for the coming year. Same-store sales for the fashion company rose 1%, but overall revenue fell a larger-than-expected 2.2%, and earnings also fell short of what investors had hoped to see because of extensive markdowns. Express also said it saw declining same-store sales in the beginning of the new fiscal year, with earnings guidance predicting a 10% to 25% drop in earnings per share from last year's levels. Until retailers stop the cutthroat discounting behavior that has plagued the industry throughout the holiday season, Express and its peers will have trouble recovering fully.

Herbalife dropped 7% after the Federal Trade Commission opened an investigation into the multi-level-marketing retailer. The company has been the subject of an intense battle between high-profile institutional investors, including Bill Ackman on one side and Carl Icahn and others on the other. With Ackman having sold the stock short and having attacked Herbalife vigorously, today's news comes as no surprise to him. But while news of an investigation is never positive, it's too early to tell whether the actual results of the civil probe will reveal anything that hurts the company's long-term prospects -- or reward those who've bet against the stock.

Interestingly, other companies with similar business models were mixed today, with USANA Health falling 4% but Nu Skin Enterprises soaring 7% despite Herbalife's news, as investors apparently concluded that Herbalife's troubles won't affect Nu Skin.