* 'Quadruple witching' may boost volume, volatility
* Oracle slumps, Carmax surges after results
* Indexes up: Dow 0.24 pct, S&P 0.2 pct, Nasdaq 0.13 pct (Updates to open, adds comment)
By Chuck Mikolajczak
NEW YORK, June 20 (Reuters) - U.S. stocks climbed on Friday, lifting the S&P index to a third straight intraday high and its sixth day of gains, with the benchmark index also poised to notch its fourth weekly advance over the past five.
Investors may see a spike of volume and volatility towards the closing bell as Friday marks a "quadruple witching" day - the expiration of stock options, index options, index futures and single-stock futures - as traders close hedging positions or roll them over at the last minute.
The six-day run of gains in the S&P index was its longest winning streak since mid-April. For the week, the index is up 1.3 percent, while the Dow is up 1.1 percent and the Nasdaq has gained 1.2 percent.
"There continues to be this hope that the economy improves, that growth improves. But for the markets, a slow steady growth environment is pretty much nirvana," said Tim Ghriskey, chief investment officer of Solaris Group in Bedford Hills, New York.
"As long as there is modest upside, that is what generally investors are looking for that unfolds over time."
Oracle Corp shares were down 5.3 percent to $40.26 as the biggest drag on the S&P 500 after it posted fourth-quarter results that disappointed investors looking for more progress against rivals selling web-based services.
But Carmax surged 14.3 percent to $51.76 as the best performer on the benchmark index after the used-vehicle retailer reported first-quarter earnings that topped analysts' expectations.
The Dow Jones industrial average rose 40.1 points, or 0.24 percent, to 16,961.56, the S&P 500 gained 3.85 points, or 0.2 percent, to 1,963.33 and the Nasdaq Composite added 5.60 points, or 0.13 percent, to 4,364.93.
Darden Restaurants lost 3.2 percent to $47.95 after the chain restaurant operator reported a much-lower-than-expected quarterly profit as costs soared and sales at its flagship Olive Garden restaurant chain fell.
Owens Corning slumped 3.8 percent to $39.71 after the company lowered its 2014 earnings forecast, citing weakness in its roofing business.
Midstream energy company Targa Resources Corp fell 9.2 percent to $136.76 after it said it was no longer in discussions with Energy Transfer Equity LP, the pipeline company controlled by billionaire Kelcy Warren, regarding a deal. The company's energy logistics operating unit Targa Resource Partners lost 12.5 percent to $71.37.
U.S.-listed shares of Shire jumped 19 percent to $228.22 after it rejected a 27 billion-pound ($46 billion) takeover offer from U.S. rival AbbVie, the latest attempt by a U.S. healthcare firm to tap into the London-listed group's low tax rate. (Editing by Bernadette Baum)