Jan 28 (Reuters) - Canada's main stock index fell on Monday as shares of energy companies were pressured by a decline in oil prices after U.S. companies added rigs, a signal that crude output may rise further.
* The energy sector .SPTTEN shed 1.7 percent, the most among the 6 major sectors in the red, as U.S. crude CLc1 prices fell 2.9 percent per barrel, while Brent crude LCOc1 lost 2.3 percent. O/R
* SNC-Lavalin Group SNC.TO plunged 19.7 percent, the most on the main index and pushed industrials .GSPTTMT 1.5 percent lower.
* The construction and engineering firm cut its forecast for full-year 2018 profit, citing a problem with a project in its mining and metallurgy unit, as well as ongoing trading challenges in the Middle East and Saudi Arabia. At 9:43 a.m. ET (14:43 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 81.86 points, or 0.53 percent, at 15,284.19.
* The Canadian dollar weakened against its U.S. counterpart, pulling back from its highest in more than two weeks as oil prices fell and investors grew more concerned over China's economy. Global stocks were pressured by a second straight monthly fall in profits for China's industrial firms. On the TSX, 79 issues were higher, while 155 issues declined for a 1.96-to-1 ratio to the downside, with traded volume touching 16.91 million shares.
* The largest percentage gainers on the TSX were Iamgold Corp IMG.TO and Alamos Gold Inc AGI.TO .
* The most heavily traded shares by volume were Critical Control Energy Services Corp CCZ.TO , Aurora Cannabis ACB.TO , and Green Organic Dutchman Holdings Ltd TGOD.TO .
* The TSX posted four new 52-week highs and one new low.
* Across all Canadian issues, there were 10 new 52-week highs and three new lows, with total volume of 35.15 million shares.