* 'Quadruple witching' may boost volume, volatility
* Oracle slumps in premarket after results
* Carmax surges in premarket after earnings
* Futures up: Dow 25 pts, S&P 3.75 pts, Nasdaq 4.75 pts (Updates prices)
By Chuck Mikolajczak
NEW YORK, June 20 (Reuters) - U.S. stock index futures pointed to a modestly higher open on Friday, putting the S&P on track to extend its record high with a sixth straight day of gains, and a fourth weekly gain over the past five.
* Investors may see a spike of volume and volatility at the open and 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.
* Oracle Corp shares were down 6.3 percent to $39.82 before the opening bell after it posted fourth-quarter results that disappointed investors looking for more progress against rivals selling web-based services.
* Five days of gains in the benchmark S&P index marked its longest winning streak since mid-April. For the week, the index is up 1.2 percent, while the Dow is up 0.9 percent and the Nasdaq has gained 1.1 percent.
* S&P 500 e-mini futures were up 3.75 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 modestly higher open. Dow Jones industrial average e-mini futures rose 25 points and Nasdaq 100 e-mini futures added 4.75 points.
* Darden Restaurants lost 4.1 percent to $48.51 in premarket trade 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 6.8 percent to $38.50 in premarket after the company lowered its 2014 earnings forecast, citing weakness in its roofing business.
* Carmax surged 16.2 percent to $52.60 after the used-vehicle retailer reported first-quarter earnings that topped analysts' expectations.
* Midstream energy company Targa Resources Corp fell 9.8 percent to $135.89 before the opening bell 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. Targa's energy logistics operating unit Targa Resource Partners lost 10.5 percent to $73.02.
* U.S.-listed shares of Shire jumped 16.5 percent to $223.31 in premarket trading 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)