TORONTO (Reuters) — The Toronto Stock Exchange’s main index extended robust gains for a second straight session yesterday, as investors appeared determined to end 2006 on a positive note.Amid a broad-based rally, the S&P/TSX composite index gained 56.95 points, or 0.44 percent, to close at 12,909.54. The advance built on Wednesday’s spike of more than 134 points.

“The last part of the year and the beginning of the new year is traditionally a very strong period for equities,” said Elvis Picardo, chief market strategist at Global Securities Corp. in Vancouver. “Now, as we’re heading towards the year-end, optimism seems to be coming back and you’re seeing interest in all the groups.”

All but one of the composite’s 10 main groups recorded increases, with the key energy and materials sectors gaining 0.4 percent and 0.62 percent, respectively. Financials advanced 0.26 percent. Health care, the sole decliner, slipped 0.32 percent. The S&P/TSX 60 index of Canadian blue chips rose 4.24 points to 743.81.

Picardo said the strong gains made by the main index during the year — to the tune of about 14 percent — along with signs of economic resilience to a potential slowdown, were among factors imbuing investors with year-end confidence.

“I think it was very hard to fathom at the beginning of this year that we would be closing 2006 at close to 13,000,” he said.

As was the case earlier this week, trading volume was relatively thin at about 193.4 million shares worth C$3.1 billion, with advancers outpacing decliners 759 to 679, and observers said no specific reason could be attributed to the day’s gains.

John Kinsey, portfolio manager at Caldwell Securities Ltd., said that financial services and commodities issues attracted interest, “but on balance, it’s very quiet here.”

Among the biggest gainers were Suncor Energy Inc., which rose C$1.12, or 1.2 percent, to C$91.86, and ACE Aviation Holdings Inc., which advanced C$1.09, or 3 percent, to C$38.09.