Hot Stocks: Amgen, Chip Stocks Among Big Movers

Earnings blowouts and encouraging drug trials were some of the catalysts behind Thursday's most actively traded stocks.

Beaten down shares of Amgen moved higher, touching an intraday high of $64.40, or 7.2%, after results from a clinical trial for anemia drug Aranesp showed no increase in risk of death compared with a placebo in a study of lung cancer patients.

The FDA recently slapped a "black box" warning label on Aranesp, Epogen and Procrit, all of which were developed by Amgen, due to safety concerns. Procrit is marketed by Johnson & Johnson under a longstanding license. Since a recent Jan. 22 high of $75.85, Amgen shares have declined 21% as of Wednesday's close.

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FTN Midwest Securities upgraded shares of both companies to "buy," saying the two rival chipmakers are moving away from the aggressing pricing war of the past year.

Linear Technology also saw a surge in trading volume as the stock added to Wednesday's gain of 12%, which followed news of the analog chipmaker's $3 billion debt-funded stock buyback. Lehman Brothers and Prudential both raised the target price on the stock on Thursday.

Spansion , the flash memory company spun off of AMD, plunged 19% after announcing a wider-than-expected first-quarter loss. Merrill Lynch attributed the shortfall to "too much capacity and too much willingness from Intel to lose money."

Shares of Downey Financial moved higher amid above-average trading volume. Last night, CNBC's Jim Cramer said it was the "best risk/reward stock I've used on this show in a long time."

Schering-Plough shares jumped 8% after the drugmaker reported quarterly earnings well above consensus expectations. Prudential analyst Tim Anderson called it a "monster beat," as earnings of 42 cents a share topped his own estimate of 30 cents as well as the Wall Street average of 29 cents. "The 'whisper' was that Schering-Plough could beat by a significant margin, and they did," Anderson said.