* Futures up: Dow 35 pts, S&P 4.25 pts, Nasdaq 0.75 pts
* Gilead falls as Express Scripts picks AbbVie treatment
* Biocryst gets FDA OK for intravenous flu drug (Adds quote, updates prices)
By Chuck Mikolajczak
NEW YORK, Dec 22 (Reuters) - U.S. stocks were poised to open modestly higher on Monday, after the benchmark S&P 500 notched its best weekly performance in nearly two months, as oil prices continued to show signs of stabilizing and ahead of data on the housing market.
Brent crude hit a high of $62.97 and WTI crude rose to as much as $58.53 amid investor confidence there would be no substantial price loss in the run-up to the new year. Brent last traded down 26 cents at $61.12 while U.S. crude was last off 0.6 percent at $56.77 after Saudi Arabia indicated it could increase its output.
"Oil is in the process of bottoming out here," said Peter Cardillo, chief market economist at Rockwell Global Capital in New York. "Backing and filling is probably what we are going to see in oil prices and that is a good sign because the bulk of the decline is over."
"The focus is obviously on the Fed being patient and that oil prices came down sharply and are seeking a level."
The benchmark S&P index rose 3.4 percent last week, boosted by a 5 percent jump over three sessions, after the U.S. Federal Reserve said it would take a "patient" approach toward raising interest rates and oil prices appeared to stabilize. The S&P energy index surged nearly 10 percent for the week.
Investors await existing home sales data, due out at 10:00 a.m. (1500 GMT). Expectations are for a decline of 1 percent.
S&P 500 e-mini futures were up 4.25 points and fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract, indicated a higher open. Dow Jones industrial average e-mini futures rose 35 points and Nasdaq 100 e-mini futures added 0.75 points.
Trading volume is expected to be light this week due to the Christmas holiday, which could increase volatility. U.S. equity markets will open for an abbreviated session Wednesday and be closed on Thursday.
Gilead Sciences is likely to weigh on the Nasdaq, as it slumped 9.9 percent to $97.75 in premarket trade. Express Scripts, the nation's largest pharmacy benefit manager, has lined up a cheaper price from AbbVie Inc on its newly approved hepatitis C treatment and, in most cases, will no longer cover Gilead's treatments.
BioCryst Pharmaceuticals gained 3.7 percent to $11.57 in premarket trade after the U.S. Food and Drug Administration approved its intravenous flu drug.
Achillion Pharmaceuticals Inc said it would test a combination of two of its experimental hepatitis C drugs which showed promise in separate studies. Its shares surged 14.4 percent to $16.25 before the opening bell.
Caesars Entertainment Corp said it would merge with affiliate Caesars Acquisition in an all-stock deal. Caesars Entertainment jumped 23.8 percent to $16.70 in premarket trade while Caesars Acquisition rose 11 percent to $10.50.
Editing by Bernadette Baum