NEW YORK (TheStreet) -- Achillion Pharmaceuticals  (ACHN) - Get Report plunged Wednesday as shares sold off from the previous two days' gains.

The company surged Monday on the news of Merck's  (MRK) - Get Report acquisition of Idenix Pharmaceuticals  (IDIX) . The stock continued to surge Tuesday after the FDA removed its clinical hold on sovaprevir, one of Achillion's four experimental hepatitis C treatments. The FDA had placed the hold in June because of abnormal liver results in patients. Achillion can now begin trials with a once-daily maximum dose of 200 mg of sovaprevir in hepatitis C patients and other healthy volunteers.

The stock was down 9.1% to $7.08 at 10:15 a.m.

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