* Philly Fed factory activity data index surges in Sept
* S&P 500 adds to record gains after Fed's stimulus decision
* Indexes: Dow flat, S&P up 0.1 pct, Nasdaq up 0.1 pct
By Angela Moon
NEW YORK, Sept 19 (Reuters) - U.S. stocks were little changed on Thursday as investors took a breather after a rally that took the S&P 500 and the Dow Jones industrial average to record levels in the wake of a surprise decision by the Federal Reserve to maintain its stimulus.
Major U.S. stock indexes seesawed between modest gains and losses in morning trading after Wednesday's rally that was sparked by the U.S. Fed's unexpected decision to keep its massive stimulus efforts intact. The Fed will continue, for now, with its $85-billion monthly bond purchases which have propped up economic growth and equity markets for much of the year.
"After the substantial move yesterday and people digesting the fact that tapering is put on hold, I don't expect a big move today. Nevertheless, we are seeing tech and small caps leading which is definitely positive for the market," said Ryan Detrick, senior analyst at Schaeffer's Investment Research in Cincinnati, Ohio.
"Now that we have one worry out of the way, I think the next big catalyst to move the market is the earnings season which is not too far away."
In economic news, factory activity in the U.S. mid-Atlantic region increased by the most in more than two years in September and firms' optimism about the future hit a 10-year high.
A separate report showed the number of Americans filing new claims for jobless benefits rose last week, though it was difficult to get a clear reading on the labor market's health because two states appeared to be working through a backlog of unprocessed claims.
News that the Fed would delay winding down its stimulus until it had more evidence of solid economic growth boosted global equity markets on Thursday, especially emerging markets as investors returned to riskier assets.
The Dow Jones industrial average was down 5.76 points, or 0.04 percent, at 15,671.18. The Standard & Poor's 500 Index was up 1.19 points, or 0.07 percent, at 1,726.71. The Nasdaq Composite Index was up 4.45 points, or 0.12 percent, at 3,788.09.
JPMorgan Chase & Co, the biggest U.S. bank, will pay approximately $920 million in penalties to regulators in two countries to settle some of its potential liabilities from its $6.2-billion "London Whale" derivatives loss last year, according to terms made public on Thursday. JPMorgan shares were down 1 percent at $52.88.
Rite Aid Corp, the third-largest U.S. drugstore chain, raised its profit forecast for the current year after reporting a fourth straight quarterly profit. The stock jumped 15 percent to $4.26.