* Dow, S&P 500 chalk up fifth straight week of gains
* S&P 500 up for a 6th straight session, but gains slight
* Manchester United debuts on NYSE near IPO price
* JCPenney shares rise as drop in customer traffic slows
* Dow up 0.3 pct, S&P 500 up 0.2 pct, Nasdaq up 0.1 pct
By Ryan Vlastelica
NEW YORK, Aug 10 (Reuters) - The Standard & Poor's 500 finished slightly higher on Friday to run its streak to six straight sessions, but activity was light and gains were slight as the market enters a seasonally slow period.
The Dow and the S&P 500 closed out their fifth straight week of gains, led once again by expectations for global central bank stimulus despite discouraging signs for growth like weak data from China.
Overall, the S&P has gained a scant 0.3 percent over the past three sessions, a sign that while investors aren't looking to cut positions, they're also reluctant to make robust moves above the three-month highs the S&P has been hovering around.
"It makes sense that we'd take a bit of a breather, but momentum has been strong, and the fact that we've held steady despite a lack of good news is a good sign the trend will continue," said Joe Bell, senior equity analyst at Schaeffer's Investment Research in Cincinnati.
Volume was incredibly light, with about 4.97 billion shares traded on the New York Stock Exchange, the American Stock Exchange and Nasdaq, well below last year's daily average of 7.84 billion.
Going nowhere on Friday were shares of Manchester United in its trading debut. The stock closed at $14, same as the initial public offering price. The IPO garnered some attention because of the high profile of the U.K. football club, but trading volume diminished shortly after it opened for trading.
The stock priced well below its expected range on Thursday, valuing the British soccer club at $2.3 billion.
Yahoo shares fell 5.4 percent to $15.15 a day after it said it may reconsider what it does with the cash it gets from a multibillion-dollar sale of half of its stake in Alibaba Group. Yahoo previously promised to return most of the cash to shareholders.
For the week, the Dow rose 0.9 percent, the S&P 500 climbed 1.1 percent and the Nasdaq advanced 1.8 percent. The Nasdaq has gained in four of the past five weeks.
The Dow Jones industrial average rose 42.76 points, or 0.32 percent, to 13,207.95 at the close. The Standard & Poor's 500 Index added 2.97 points, or 0.21 percent, at 1,405.77. The Nasdaq Composite Index advanced 2.22 points, or 0.07 percent, to close at 3,020.86.
Data on Chinese trade and bank lending suggested pro-growth policies have been insufficient in the face of weak demand from China's trading partners, and more urgent government action may be needed to stabilize the economy. Data on Chinese exports included a 16 percent decline in shipments to Europe from a year ago.
Trading has been relatively light in August, ahead of what is anticipated to be a busier September when market participants return from summer holidays and central banks, including the Federal Reserve and the European Central Bank, may swing into action.
The European Central Bank is expected to act soon, though not before September, to lower punishing borrowing costs for Spain and Italy as a way to stabilize the euro zone's economy.
Cyclical stock sectors, including financials, energy, materials and consumer discretionary names, fell, while defensive plays like telecom and health care rose.
The expectation of central bank action, however, may give support to equities as investors think twice about shorting the market on the possibility of any action.
"We're looking ahead to see what action comes from the Fed and European Central bank, and it's possible we'll consolidate until then, and then rally," Bell said.
Some economists said China's central bank could move as early as this weekend to ease policy. It has reduced banks' required reserve ratio in three steps since November to free up new lending and cut interest rates in June and July.
Research In Motion's U.S.-traded shares rose 6.3 percent to $8.29 after Bloomberg reported IBM Corp has considered buying RIM's enterprise division.
Fusion-io Inc shares jumped nearly 28 percent to $26.86 after the company's projection late Thursday of strong growth over the next year and the storage drive maker handily beat fourth-quarter profit estimates.
J.C. Penney shares rose 5.9 percent to $23.40 as the company said its second-quarter results showed a slowing in the flight of long-time customers reacting to a new pricing policy.
About 52 percent of stocks traded on the New York Stock Exchanged closed in positive territory, while only 42 percent of Nasdaq-listed shares finished higher.