* TSX falls 12.42 points, or 0.08 percent, to 15,430.25
* Four of the TSX's 10 main groups decline
TORONTO, March 27 (Reuters) - Canada's main stock index seesawed on Monday as lower oil prices weighed on the energy sector, offsetting gains for gold shares amid heightened demand for safe-haven assets like precious metals.
On global markets, U.S. President Donald Trump's failure to win enough congressional support for medical insurance reform was bearish for stocks but bullish for government bonds, whose yields fell.
The financials group lost 0.3 percent. Manulife Financial Corp dropped nearly 2 percent to C$22.94, and Toronto-Dominion Bank declined 0.6 percent to C$64.81.
Higher bond yields would reduce the value of insurance companies' liabilities and increase net interest margins of banks.
The energy group fell 0.8 percent as oil prices declined on uncertainty over whether an Organization of the Petroleum Exporting Countries-led production cut will be extended beyond June in an effort to counter a glut of crude.
U.S. crude prices were down 1.44 percent at $47.28 a barrel, while Suncor Energy Inc fell 0.8 percent to C$40.53.
At 10:40 a.m. ET (1440 GMT), the Toronto Stock Exchange's S&P/TSX composite index shed 12.42 points, or 0.08 percent, to 15,430.25.
The TSX had ended last week with two straight days of gains after Canada's government held off from raising taxes on investors in its budget, and the United States approved TransCanada Corp's Keystone XL pipeline.
On Monday, four of the index's 10 main groups were lower.
The materials group, which includes precious and base metals miners and fertilizer companies, added 0.8 percent, with Barrick Gold Corp climbing 1.4 percent to C$26.07.
Spot gold was up 1.2 percent at $1,259.11 an ounce, having touched a one-month high earlier in the session. (Reporting by Fergal Smith Editing by W Simon)