Premarket Movers: GTXI AAPL SKIL

GTx said an independent group determined that a clinical trial of Acadopene should continue. The trial could have been stopped early if the drug met predetermined levels of effectiveness.

The stock shed $2.56, or 15.8 percent, to $13.68, in the premarket session, having finished at $16.24 Thursday.

Cowen and Company analyst Eric Schmidt said the move shows the drug did not reduce the incidence of prostate cancer by 28 to 30 percent, or more, compared with a placebo.

"The news is disappointing as it suggests acadopene is less likely to succeed in this very large, underserved market opportunity," he wrote in a note to clients.

Shares of Dutch chip equipment supplier ASML Holdings NV lost 69 cents, or 2.3 percent, to $29.05 after UBS analyst downgraded the stock to "Neutral" from "Buy." U.S.-traded shares of ASML finished at $29.74 Thursday.

And education software company SkillSoft PLC's fiscal first-quarter report sent shares down 80 cents, or 7.6 percent, to $9.74 in the premarket session, having closed at $10.54 Thursday.

It appeared stocks overall would open lower as the price of oil edged upward, and the market anticipated a report on existing home sales from the National Association of Retailers. Analysts expect a decline of 1.6 percent from a year ago.

On the positive side, analyst comments lifted Apple Inc. shares $3.95, or 2.2 percent, to $181 from $177.05.

Goldman Sachs analyst David Bailey placed the Cupertino, Calif.-based company's stock on the Conviction Buy List, a portfolio of recommended securities, and raised his price target to $220 per share from $185. He expects Apple to launch a new iPhone next month and said sales of the device should top Apple's goal of 10 million.