US STOCKS-Wall Street edges up to extend weekly gains

* Blackberry (Swiss: BB.SW - news) falls after results

* Brent holds above $60 a barrel

* Indexes up: Dow 0.12 pct, S&P up 0.28 pct, Nasdaq off 0.26 pct (Updates to late morning)

By Chuck Mikolajczak

NEW YORK, Dec 19 (Reuters) - U.S. stocks advanced modestly on Friday, extending gains after the best two-day run for the benchmark S&P 500 in three years was sparked by the Federal Reserve's most recent policy statement.

The S&P had climbed 4.5 percent over the previous two sessions, spurred by the U.S. Federal Reserve's commitment to take a "patient" approach toward raising interest rates, while signaling it was on track to boost rates in 2015. That provided clarity and relief to investors over the policy outlook, analysts said.

Brent crude oil advanced above $60 a barrel on Friday, recovering from near a 5-1/2-year low, while WTI crude climbed 3.3 percent to $55.90.

The S&P 500 has risen more than 3 percent this week, putting it on track for its best weekly performance in two months. This index has erased nearly all of the losses from the prior week, which were spurred by a sharp drop in oil prices.

"Basically, all we are doing is recovering from the oil-induced selloff. It's kind of coming back to where we were about two weeks ago," said Peter Jankovskis, co-chief investment officer at OakBrook Investments LLC in Lisle, Illinois.

"We have digested the drop in oil, we have gotten past the Fed, and now we will see what we will do for the rest of the year."

The Dow Jones industrial average rose 20.53 points, or 0.12 percent, to 17,798.68, the S&P 500 gained 5.84 points, or 0.28 percent, to 2,067.07 and the Nasdaq Composite added 12.54 points, or 0.26 percent, to 4,760.93.

Equity trading may be volatile Friday due to "quadruple witching," the expiration of stock options, index options, index futures and single-stock futures. In addition, the rebalance of the S&P 500 is scheduled to take effect after the close.

U.S.-listed shares of Blackberry dropped 6.4 percent to $9.43 after the company posted a small adjusted third-quarter profit and returned to positive cash flow, but revenue declined more than expected.

Nike (Sao Paolo: NIKE34.SA - news) shares were down 3.7 percent to $93.51, a drag on both the Dow and S&P 500, after its quarterly results.

Cerus Corp shares jumped 8 percent to $6.65 after the company said the U.S. Food and Drug Administration approved its blood transfusion device for platelets.

Shares (Berlin: DI6.BE - news) in Ally Financial (NYSE: ALLY - news) were up 4 percent to $23.65. The company said the U.S. Treasury Department will sell the remaining 54.9 million shares acquired under the government's bailout of the auto lender.

Advancing issues outnumbered decliners on the NYSE 1,648 to 1,292, for a 1.28-to-1 ratio; on the Nasdaq, 1,372 issues fell and 1,201 advanced, for a 1.14-to-1 ratio favoring decliners.

The benchmark S&P 500 was posting 102 new 52-week highs and 5 new lows; the Nasdaq Composite was recording 80 new highs and 29 new lows. (Editing by Bernadette Baum and Nick Zieminski)