(Adds details on sectors and stocks throughout, updates prices)
* TSX down 12.78 points, or 0.09 percent, at 13,898.51
* Six of the TSX's 10 main groups were lower
TORONTO, April 21 (Reuters) - Canada's main stock seesawed on Thursday as losses for financial sector stocks offset gains for the materials group.
Still, the index has rallied more than 20 percent since hitting a nearly 3-1/2-year low in January. It reached a nearly six-month high on Wednesday at 13,971.83.
The most influential movers on the index included its heavyweight bank stocks. Royal Bank of Canada fell 0.6 percent to C$77.43, and Toronto-Dominion Bank declined 0.4 percent to C$56.15.
The overall financials group fell 0.6 percent.
Bombardier Inc fell 2.9 percent to C$1.69. Canada will not give the struggling aircraft maker federal aid without assurances on jobs, investment in research and the location of the company's headquarters, a senior government official said on Wednesday.
The energy group dipped 0.1 percent as oil prices fell. U.S. crude was down 1.9 percent at $43.34 a barrel.
Consumer staples stocks also lost ground, falling 0.8 percent. Alimentation Couche-Tard Inc was down 1.8 percent at C$57.02.
At 10:49 a.m. EDT (1449 GMT), the Toronto Stock Exchange's S&P/TSX composite index fell 12.78 points, or 0.09 percent, to 13,898.51. Six of the index's 10 main groups were lower.
The materials group, which includes precious and base metals miners and fertilizer companies, rose 1.6 percent.
Barrick Gold Corp rose 3.2 percent to C$20.71, while Potash Corp of Saskatchewan Inc rallied 2.8 percent to C$23.37.
Spot gold rose 0.5 percent. (Reporting by Fergal Smith; Editing by Lisa Von Ahn)