TORONTO - North American stock markets registered steep, triple-digit losses mid-afternoon in the wake of a variety of negative economic and corporate news.

Toronto's S&P/TSX composite index snapped a six-session winning streak to tumble 326.3 points to 9,145.8.

New York's Dow Jones industrials declined 236 points to 8,779.1 as a private sector employment report raised fears that Friday's non-farm jobs report for December will come in much worse than expected and chip maker Intel said fourth-quarter revenue missed expectations.

The slide on the TSX came after the main index gained more than five per cent since the start of 2009 as investors snapped up beaten-down energy and base-metals stocks.

All TSX sectors were lower, led by declining energy and base metals stocks amid predictions from some of Canada's top economists of more financial troubles for Canada in 2009 and a slow recovery.

At a gathering of economic minds at the Economic Club of Canada in Toronto, they said the global economic meltdown will continue to affect the country for at least the first half of the year before it returns to growth, which will likely be lower than normal.

The TSX Venture Exchange moved 22.52 points lower to 890.59 while the Canadian dollar shed 0.83 cent to 83.73 cents US.

The ADP National Employment Report said private sector employment fell by 693,000 in December.

Economists had been expecting a drop of about 490,000 jobs in the U.S. last month.

The Nasdaq composite index lost 52.88 points to 1,599.5 after chip maker Intel said it expects fourth-quarter revenue to fall 23 per cent from the same period a year earlier. It said it is missing its previous outlook because of ongoing weak demand and inventory reductions by its PC maker customers and its shares fell 77 cents to US$14.60.

The S&P 500 index gave back 26.7 points to 908.

"Markets are grabbing on any data that they can get to and (while) the ADP report hasn't been an appropriate predictor of what the employment figures will be but they give you a sense of the direction," said Norman Raschkowan, chief investment officer at Mackenzie Financial Corp.

"Intel was obviously disappointing and of course the Fed's release yesterday of the minutes from their last meeting where they're talking about the recession being deeper and longer and then (Obama) talking about trillion-dollar deficits for a number of years going forward -- people woke up this morning with all sorts of news reminding them we're not out of the woods yet."

And media industry bellwether Time Warner Inc. said it would take a US$25 billion impairment charge in the fourth quarter for its cable, publishing and AOL units. The news sent its shares down 71 cents to US$10.27.

Another reminder of deteriorating employment levels came late Tuesday after aluminum producer Alcoa Inc. said it is reducing its global work force by about 13,500, or 13 per cent, by the end of the year and lowering total output by more than 18 per cent annually. Its shares tumbled $1.20 to US$10.92.

"The market has shrugged off some bad news recently, and it's starting to get to the point where it can't do that anymore," said Scott Fullman, director of derivatives investment strategy for WJB Capital Group in New York.

The TSX energy sector was down 5.5 per cent as crude prices retreated after running up about $10 a barrel over the last week, in large part because of the Israeli offensive in Gaza.

The February crude contract on the New York Mercantile Exchange fell $5.42 to US$43.16 a barrel as demand concerns trumped worries over the Mideast after a government report showed U.S. oil reserves were much bigger than expected last week.

EnCana Corp. (TSX:ECA) declined $3.34 to $57.52 while Suncor Inc. (TSX:SU) eased $1.91 to $27.11.

Enterra Energy Trust (TSX:ENT.UN) says it may limit capital spending due to falling commodity prices. Its units were off eight cents to 80 cents as the company said it is looking for alternative investment opportunities besides a conventional drilling program.

The financial sector stepped back 2.2 per cent as Royal Bank (TSX:RY) gave back 79 cents to $37.95 and Manulife Financial (TSX:MFC) dropped 99 cents to $23.12.

The base metals sector declined eight per cent as March copper dropped 4.5 per cent to US$1.51.15 a pound with Teck Cominco Ltd. (TSX:TCK.B) down 51 cents to $7.68 and Sherritt International (TSX:S) lost 55 cents to $3.90.

The gold sector was down six per cent as the February bullion contract in New York fell $24.30 to US$841.70 an ounce. Goldcorp Inc. (TSX:G) faded $1.64 to $33.50.

Consumer discretionary stocks were also in the red with shares in auto parts maker Magna International (TSX:MG.A) down $3.33 to $38.98.

General Motors Corp. has cancelled plans to build the Pontiac G8 sport truck that was scheduled to go on sale this year.

Pontiac spokesman Jim Hopson says the move is part of GM's "ongoing review" related to its long-term viability plan and that the sport truck didn't fit with the company's vision for Pontiac. GM shares added 12 cents at US$4.06.

Major air carriers WestJet (TSX:WJA) and Air Canada (TSX:AC.A) had fewer empty seats in December despite economic hurdles and weather-related challenges.

Calgary-based WestJet reported a load factor of 80.9 per cent for the month, up 1.6 percentage points from 79.3 in December 2007 as the airline increased capacity 10.6 per cent.

Air Canada reported a load factor of 81.7 per cent, up 2.9 percentage points from the same month a year earlier as it cut capacity 9.9 per cent, dropping system traffic by 6.6 per cent.

WestJet shares climbed 27 cents to $13.01 while Air Canada dipped eight cents to $1.78.

Reitmans (Canada) Ltd. (TSX:RET.A) shares fell 30 cents to $10.40 after it said its same-store sales decreased by 5.4 per cent in December.

Sales for the year decreased slightly to $1.001 billion from $1.004 billion in 2007.