The TSX, which has rallied more than 7 percent since August, moved above the 16,000 threshold this week for the first time.

"You are going to see some profit-taking as you go through these strategic numbers, said Bruce Latimer, senior equity trader at Eight Capital. "People are going to lighten up some positions and see where they can apply cash on the next move."

Investors assessed U.S. President Donald Trump's pick of Jerome Powell to lead the Federal Reserve and the long-awaited tax cut plan unveiled by Trump's fellow Republicans.

Enbridge Inc (>> Enbridge Inc) was the biggest drag on the index, accounting for some 28 points on the downside, after its shares fell 4.8 percent to C$47.03 on news that quarterly profit missed estimates.

Imperial Oil (>> Imperial Oil Ltd) slumped 5.5 percent to C$39.17 following several ratings cuts from analysts.

Still, higher oil prices provided some support for the energy sector.

U.S. crude prices settled up 0.4 percent at $54.54 a barrel, boosted by OPEC-led supply cuts which have tightened the market and drained inventories.

The Toronto Stock Exchange's S&P/TSX composite index <.GSPTSE> closed down 14.34 points, or 0.09 percent, at 16,014.99. On Wednesday, it touched an all-time intraday high of 16,105.88 and locked in a record close.

The materials group, which includes precious and base metals miners and fertilizer companies, was one of five of the index's 10 main groups that lost ground. It retreated 0.4 percent, with Potash Corporation of Saskatchewan Inc (>> Potash Corporation of Saskatchewan Inc) sliding 1.7 percent to C$24.86.

Sleep Country Canada Holdings (>> Sleep Country Canada Holdings Inc) tumbled 13.0 percent to C$33.58 after the mattress company reported a quarterly profit that missed estimates and analysts cut their ratings and price targets.

BCE Inc (>> BCE Inc.) was the most influential gainer on the index, advancing 1.7 percent to C$60.47 after posting a better-than-expected quarterly profit.

The financials group, which accounts for 35 percent of the TSX's weight, gained 0.4 percent.

Kinaxis Inc (>> Kinaxis Inc) jumped 12.1 percent to C$70.96 after posting a quarterly profit that beat forecasts, while the broader technology sector gained 0.9 percent.

(Additional reporting by Solarina Ho; Editing by Bernadette Baum and Leslie Adler)

By Fergal Smith