US STOCKS-Wall St falls as rally stalls; Greece eyed
* "Quadruple witching" to add to volatility
* Indexes set to for best week in about two months
* ConAgra rises after Jana Partners takes stake in company
* Indexes down: Dow 0.21 pct, S&P 0.16 pct, Nasdaq 0.16 pct (Adds details, changes comment, updates prices)
By Tanya Agrawal
June 19 (Reuters) - Wall Street fell in late morning trading on Friday, a day after a strong rally pushed the Nasdaq Composite index to a record high, but the major indexes were still on track for their strongest weekly performance in about two months.
The Nasdaq Composite broke its last standing milestone from the dot-com era on Thursday, while the S&P 500 rose to within 0.5 percent of its record high on the Fed's perceived dovishness regarding the pace of a rate hike.
U.S. stocks were also affected on Friday by the "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 Greece crisis also showed no signs of receding. Euro zone leaders will hold an emergency summit on Monday to try to avert a Greek default after bank withdrawals accelerated and government revenue slumped as the debt talks drag on. Continuación...