* TSX down 44.51 points, or 0.27 percent, at 16,177.44
* Nine of the TSX's 10 main groups move lower
* Index eyes 6 pct gain in 2017, boosted by financials, miners
TORONTO, Dec 29 (Reuters) - Canada's main stock index fell early on the last trading day of 2017 as some energy and mining stocks pulled back, but was on track for a nearly 6 percent gain for the year.
* At 9:51 a.m. EST (1451 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 44.51 points, or 0.27 percent, at 16,177.44, with nine of its 10 main sectors in negative territory.
* Marijuana stocks helped push the healthcare group higher, with Canopy Growth Corp WEED.TO up 4.6 percent to C$31.82 and Aphria Inc APH.TO up 4.3 percent to C$18.78. Canada is moving towards the full legalization of cannabis in 2018.
* The materials group, which includes precious and base metals miners and fertilizer companies, lost 0.6 percent.
* That was despite gains for Potash Corp of Saskatchewan Inc POT.TO , up 1.5 percent to C$26.21, and Agrium Inc AGU.TO , up 1.4 percent to C$146.17. The two companies received final approval for a merger earlier in the week. Hudbay Minerals Inc HBM.TO fell 3.2 percent to C$10.99, First Quantum Minerals Ltd FM.TO was down 2.6 percent to C$17.45, and Teck Resources TECKb.TO lost 1.9 percent to C$32.83.
* The energy group retreated 0.4 percent, while financials also lost 0.4 percent.
* The energy group has lost almost 13 percent this year, even as U.S. crude oil prices rose 12 percent, while materials were up 6 percent and financials added 9 percent. Those three groups account for almost two-thirds of the index's weight.