can't/won't be good for NOT and area plays today....

TORONTO (Reuters) - The Toronto Stock Exchange's main index, beholden to its big resource shares, was set to fall on Thursday as anxiety over the global credit crunch infected commodity prices for a second straight day.

After a volatile three days, the index is off more than 4 percent as its biggest sectors -- financials on Monday, and materials and energy on Wednesday -- dragged it down.

The TSX dropped 3.25 percent in the previous session and appears to be in for more pain on Thursday, with key commodities tumbling across the board.

"A big part of this is speculative supply-and-demand in commodities, which recently were the only ones rising," said Beste Alpargun, vice-president of equity research at Citadel Securities in Halifax, Nova Scotia.

"I see this as a panic situation, but of course in every panic situation there is something fundamental going on -- and expectations are very important."

Crude oil futures fell below $100 a barrel for the first time in two weeks as investors priced in the likelihood of declining U.S. energy demand.

Natural gas, the other key indicator for the TSX energy sector, was down more than 3 percent.

Meanwhile, the prices of both spot gold and copper futures fell to one-month lows on expectations of a slowing global economy.

Oil, gas and materials issues represent about half of the main Canadian index, and have grown in prominence this year as the credit crisis deflates financial issues.

In an otherwise quiet morning, U.S. data showed an unexpectedly large rise in the number of workers filing for jobless benefits. Still, U.S. stock futures pointed to a slightly higher open.

Canada's S&P/TSX composite index <.GSPTSE> starts the day at 12,709.38 after falling 427.32 points in the previous session, its worst day in nearly two months.

(Reporting by Jonathan Spicer; Editing by Scott Anderson)