*TSX down 10.29 points at 12,372.53
*Five of 10 sectors weaker (Updates with details, commentary)
By Claire Sibonney
TORONTO, Sept 30 (Reuters) - Toronto's main stock index tread water on Thursday morning, after hitting its highest level in two years the day before, as rising commodity prices and bullish U.S. data were undermined by declining gold miners and volatility on the last day of the third quarter.
The upbeat U.S. economic news pulled prices for safe-haven gold off record highs, sending the index's precious metal miners down 2 percent. Barrick Gold Corp ABX.TO, the world's No. 1 gold producer, fell 2.8 percent to C$47.19.
New U.S. claims for jobless benefits fell last week, pointing to a modest strengthening in the labor market, while second-quarter U.S. growth was revised a touch higher on firmer consumer spending. U.S. Midwest business activity also beat forecasts.
Oil prices rose after the U.S. data offered hope for a pick-up in economic activity in the world's largest economy, sending energy shares up 0.4 percent. Suncor Energy SU.TO gained 0.3 percent to C$33.30.
Economically sensitive base-metal miners and financials also rose. Teck Resources TCKb.TO advanced 1.1 percent to C$42.41, and Royal Bank of Canada RY.TO added 0.5 percent to C$53.94.
"This goes on record right now as one of the better Septembers we've had in North American equity markets, whether it's Toronto or New York," said Bruce Latimer, a trader at Dundee Securities.
Latimer warned that trading could be volatile through Thursday as fund managers and large institutional investors take profits or reposition their portfolios on the last day of the month and the third quarter.
"It's certainly a positive and bullish feeling but I think people are being cautious as we move higher because there's just no rush to jump into the equity market," he said.
At 10:29 a.m. (1429 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 10.29 points, or 0.08 percent, at 12,372.53. Five of the index's 10 sectors were weaker. On Wednesday, the index closed at 12,382.82, its highest level since September 2008.
Potash Corp POT.TO slipped 1.2 percent to C$148.48 after sources said China's top chemicals company, Sinochem, is working hard to come up with a challenge to BHP's $39 billion bid for the world's largest fertilizer maker, but that efforts to secure a Russian partner have failed. [ID:nSGE68T015]
Bombardier Inc BBDb.TO rose 1.4 percent to C$5.02, after announcing said it will proceed with plans to expand its Global family of large business aircraft and will unveil details next month. [ID:nN30151869]
($1=$1.03 Canadian) (Editing by Peter Galloway)