TORONTO (Reuters) - The Toronto Stock Exchange's main index ended lower for a second straight session, as a retreat in materials and energy issues offset strength from news of a big Russian investment in autoparts maker Magna International.The S&P/TSX composite index closed down 42.03 points, or 0.3 percent, at 13,853.13.

Six of the TSX index's 10 main groups were lower, led by a 0.9 percent slump in the resource-heavy materials issues amid weak metals prices.

"Commodity stocks are down because commodity prices and gold prices are down," said Elvis Picardo, investment strategist at Northern Securities in Vancouver.

"The energy group as a whole is down despite crude oil prices being up. That disconnect is caused by a lack of conviction among investors that today's gains in crude oil are sustainable."

Picardo added that disappointing economic data south of the border likely dampened investor sentiment, while some profit-taking in select stocks is expected given the market's recent record-setting pace.

Shares of Lundin Mining slipped 83 Canadian cents, or 5.7 percent, to C$13.75. Earlier Thursday, the mid-tier miner posted a big jump in first-quarter earnings, reflecting its merger with EuroZinc last year, but lower metal prices and shipments pushed profits below expectations.

Inmet Mining shed C$2.01, or 2.7 percent, to C$73.80.

A drop in gold prices also weighed on the market with shares of Barrick Gold, the world's biggest producer, off 91 Canadian cents, or 2.7 percent, at C$33.28.

The heavyweight energy sector slid 0.6 percent despite a rise in US June crude prices, which climbed 26 cents to settle at $61.81 a barrel.

Shares of Canadian Natural Resources fell 79 Canadian cents, or 1 percent, to C$69.15, while Suncor Energy dipped C$1.20, or 1.3 percent, to C$91.15.

The retreat in the two sectors offset strength from Magna, which jumped C$6.42, or 7.4 percent, to C$93.65 on news of a $1.54 billion investment in the autoparts maker from Russian billionaire and automotive entrepreneur Oleg Deripaska.

Magna, which is looking to buy a stake in DaimlerChrysler's struggling US-based Chrysler Group, also reported a 2.8 percent rise in first-quarter profit on stronger revenues.

"I think we're going to have some choppiness but the bull market is still very much alive," said John Ing, president of Maison Placements Canada.