May 4 (Reuters) -
* The Toronto Stock Exchange's S&P/TSX .GSPTSE rose 107.93 points, or 0.69 percent, to 15729.4.
* The biggest contributor to the TSX gain was Canadian National Railway CNR.TO with 11.68 net index points. Energy was the top sector contributor with 33.38 net points.
* Leading the index were Martinrea International Inc, up 10.2 percent, Pason Systems Inc, up 9.4 percent, and Nevsun Resources Ltd, higher by 8.8 percent.
* Lagging shares were Gildan Activewear Inc, down 5.2 percent, Altus Group Ltd, down 4.0 percent, and Enerflex Ltd, lower by 4.0 percent.
* On the TSX 169 issues advanced and 74 declined as a 2.3-to-1 ratio favored advancers. There were 8 new highs and 2 new lows, with total volume of 180.6 million shares.
* The most heavily traded shares by volume were Baytex Energy Corp, Bombardier Inc and Manulife Financial Corp.
* The TSX's energy group .SPTTEN rose 1.32 points, or 0.67 percent, while the financials sector .SPTTFS climbed 1.09 points, or 0.37 percent.
* West Texas Intermediate crude futures CLc1 rose 1.94 percent, or $1.33, to $69.77 a barrel O/R
* The TSX is off 3 percent for the year. (Editing by Alden Bentley)