(Fixes second paragraph to show it was crude's lowest settlement since May 2005, not May 25)
*TSX sinks 9.3 pct; erases Friday's 5.9 rise
*Energy shares fall as oil falls below $50 barrel (Adds official close, quote)
By Cameron French
TORONTO, Dec 1 (Reuters) - The Toronto Stock Exchange's main index tumbled more than 864 points on Monday, its worst net drop, as sliding commodity prices, gloomy U.S. economic news, and the urge to take profits after six-straight days of gains prompted a sell-off that hit every market sector.
Resource issues led the market lower as energy shares were stung by OPEC's deferral of any new oil supply cuts. U.S. crude sank $5.15 to $49.28 a barrel, its lowest settlement since May 2005.
Materials stocks were undercut by falling gold prices and an increasingly gloomy economic view, including a declaration that the United States has been in recession for the past year.
The S&P/TSX composite index .GSPTSE fell 9.3 percent to 8406.21. The percentage decline was the second biggest ever.
On a net basis, Monday's fall beat the last record set on Sept. 29.
All 10 TSX subgroups fell, with materials issues dropping 13.7 percent, and energy stocks falling 13.3 percent on the back of oil's 9 percent drop.
Financial services, which along with the resource sectors make up the bulk of listed stocks, fell 8.4 percent, hurt by the economic reports -- which included data showing falling U.S. factory activity -- and concerns about more losses for U.S. bank Citigroup (C.N).
"It's an ugly day today," said John Ing, president of investment dealer Maison Placements in Toronto.
"The lack of consensus as far as OPEC was concerned, the continuation of the talk about Citibank -- all of these contributed to a lousy market."
Among energy stocks, Talisman Energy TLM.TO dropped C$2.14, or 17.2 percent, to C$10.27, while Suncor Energy (SU.TO) retreated C$4.65, or 16.3 percent, to C$23.90.
In the materials sector, Goldcorp (G.TO) plunged C$5.85, or 16.7 percent, to C$29.15, while Teck Cominco TCKb.TO fell C$1.04, or 17.3 percent, to C$4.96.
$1=$1.25 Canadian Reporting by Cameron French; Editing by Jeffrey Jones