* TSX down 13.92 points, or 0.09 percent, at 16,015.72
* Six of the TSX's 10 main groups move lower
TORONTO, Nov 29 (Reuters) - Canada's main stock index ticked lower on Wednesday, hurt by a sharp fall in the shares of Canadian National Railway Co CNR.TO , while an earnings beat helped push Royal Bank of Canada RY.TO higher.
* At 10:15 a.m. ET (1515 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 13.92 points, or 0.09 percent, at 16,015.72.
* CN Rail fell as much as 4.9 percent, to its lowest level since March, and was last down 2.8 percent at C$97.18. Its main rival, Canadian Pacific Railway Ltd CP.TO , said it was adding several senior sales executives. Royal Bank of Canada RY.TO rose 0.6 percent to C$101.06 after the country's biggest bank by market value reported fourth-quarter earnings that beat expectations. Shopify Inc SHOP.TO fell 4.6 percent to C$136.89, erasing gains the e-commerce software company's stock had made after the Black Friday and Cyber Monday shopping days.
* The materials group, which includes precious and base metals miners and fertilizer companies, lost 0.7 percent as prices for gold as well as copper, aluminum and other base metals fell. GOL/ MET/L
* Potash Corp POT.TO added 0.9 percent to C$25.16 after its chief executive said he expects a "very tight" balance of potash supply and demand in 2018 and that the company had received "broad interest" from Chinese buyers interested in its stake in a Chilean lithium producer. Six of the index's 10 main sectors were lower, with decliners and advancers evenly matched overall.