* Bullard says stimulus could wind down from October
* Trading volume heavier than normal on quadruple witching
* FireEye, Rocket Fuel shares make their trading debut
* Both open more than 100 pct above IPO price
* Dow off 0.3 pct; S&P off 0.2 pct; Nasdaq up 0.1 pct
By Angela Moon
NEW YORK, Sept 20 (Reuters) - U.S. stocks edged slightly
lower on Friday following comments by a senior Federal Reserve
official that sparked concerns that the central bank's stimulus
efforts could be scaled back from October.
Trading volume was heavier than usual as Friday marks the
"quadruple witching," when stock index futures, stock index
options, stock options and single stock futures all expire on
the same day. Trading increases as investors replace or
repurchase existing contracts.
In addition, all three major U.S. stock indexes, as well as
the FTSE and U.S. index trackers, will rebalance their
portfolios to match revisions to index weights. This happens at
the close of trading, which could push trading volume higher as
transactions jump at the exact close.
"Since the largest of these products which are index futures
and options expire on the open, the effect is most pronounced at
the open. However, with stock and ETF expirations, as well as
index rebalancing, occurring at the close, there can also be
significant impact on the close," said Ana Avramovic,
derivatives Strategist at Credit Suisse in New York, in a note
Investors waited to see if speeches by several U.S. Federal
Reserve officials later in the day would shed light on the Fed's
surprise decision Wednesday to maintain stimulus for now and how
much longer the program was likely to continue.
"The Fed wants everyone to speak their minds to show that
the governors, officials within the Fed all have differing
opinions, that there isn't a unifying voice," said Timothy
Ghriskey, co-founder of Solaris Asset Management in Bedford
Hills, New York.
"They want the uncertainty because they don't want the
market to be surprised by anything. They want the financial
markets to ease into change."
The Nasdaq was supported by shares of Apple Inc,
which rose 0.6 percent to $474.91 as the company's latest
version of its iPhone product line hit stores around the world.
The Dow Jones industrial average was down 39.24
points, or 0.25 percent, at 15,597.31. The Standard & Poor's 500
Index was down 3.05 points, or 0.18 percent, at
1,719.29. The Nasdaq Composite Index was up 1.84
points, or 0.05 percent, at 3,791.22.
Helped by a rally that took the Dow and the S&P 500 to
record highs on Wednesday following the Fed's decision, both
indexes are now on track for a third consecutive week of gains.
In company news, Cybersecurity company FireEye Inc
shares opened 101.5 percent above its initial public offering
price at $40.30.
Shares of advertisement technology company Rocket Fuel Inc
also more than doubled in their trading debut, valuing
the company at more than $2 billion, a day after it priced its
IPO at the top end of its revised price range. The stock opened
up 106.7 percent above its IPO price at $59.95.
In an interview on Bloomberg TV early Friday, St. Louis
Federal Reserve Bank President James Bullard said a wind-down of
the Fed's $85-billion monthly bond purchase program from October
was possible. On Wednesday, the Fed surprised economists and
investors with its decision to delay scaling back stimulus from
Several senior Federal Reserve officials are scheduled to
speak Friday at various events.
Bullard speaks on monetary policy to the New York
Association for Business Economics at 12:55 p.m. EDT (1655 GMT).
Just ahead of that, Kansas City Federal Reserve Bank
President Esther George delivers a speech on the economy to the
Shadow Open Market Committee in New York at 12:30 p.m.
Federal Reserve Governor Daniel Tarullo speaks on
macroprudential regulation in New Haven, Connecticut at 12:40
Minneapolis Federal Reserve Bank President Narayana
Kocherlakota talks at a conference on risk in options prices in
New York at 1:45 p.m. EDT.
In Washington, Republicans in the U.S. House of
Representatives were expected to vote for a bill to gut
President Barack Obama's healthcare law while temporarily
funding other government programs, ignoring a warning from the
White House that the measure would be vetoed.