By Chuck Mikolajczak

NEW YORK (Reuters) - A gauge of global stocks held near flat on Monday after bouncing between gains and losses as investors questioned whether likely stimulus measures from the world's central banks would be enough to deter slowing growth, while the pound hit a six-week high in choppy trading.

After two straight weeks of gains that boosted the S&P 500 by 4.6%, stocks on Wall Street closed near the unchanged mark as advances in energy <.SPNY> and financial <.SPSY> shares were offset by a decline in tech <.SPLRCT> and healthcare <.SPXHC>.

Earlier, data showed Japan's economy grew at a slower pace than initially estimated in the second quarter as the U.S.-China trade war prompted a downward revision of business spending, intensifying calls for the central bank to deepen stimulus this month.

Still, barring a major announcement on trade developments between the United States and China, stock movements were likely to be muted ahead of the next policy announcement by the Federal Reserve on Sept. 18. Investors have begun to question whether central banks even have enough measures at their disposal to support economic growth.

The European Central Bank is expected to introduce new stimulus measures at its meeting on Thursday.

"This is kind of the eye of the storm," as investors await more news on trade or interest rates, said Paul Nolte, portfolio manager at Kingsview Asset Management in Chicago.

But he said, "for the market to move significantly higher from here, we'd really need to see something happen on trade."

Federal Reserve Board Chairman Jerome Powell said the central bank would continue to "act as appropriate" to sustain U.S. economic expansion.

The Dow Jones Industrial Average <.DJI> rose 38.05 points, or 0.14%, to 26,835.51, the S&P 500 <.SPX> lost 0.28 points, or 0.01%, to 2,978.43 and the Nasdaq Composite <.IXIC> dropped 15.64 points, or 0.19%, to 8,087.44.

European shares ended lower as Britain's export-heavy FTSE index tumbled due to a stronger pound, while selling in defensive sectors such as healthcare and utilities dented early gains in markets.

The pan-European STOXX 600 index <.STOXX> lost 0.28% and MSCI's gauge of stocks across the globe <.MIWD00000PUS> shed 0.01%.

Sterling hit a six-week high of $1.2382 <GBP=> as investors saw the likelihood of a "no-deal" Brexit lessening and data that indicated Britain's economy picked up more than anticipated in July.

British Prime Minister Boris Johnson will ask Parliament a second time for an early national election but was likely to be defeated in a vote at around 2230 GMT on Monday. He will then suspend Parliament until Oct. 14.