The Toronto Stock Exchange kicked off the month of December with a sharp plunge of more than 9% on Monday, erasing a large chunk of the gains made in last week’s trading.

All 10 main groups on the TSX moved lower, pulling the S&P/TSX composite index down 864.41 points, or 9.32%, to 8,406.21.

Tumbling commodity prices sent shares of both energy and materials companies into a freefall, plunging 13.3% and 13.7% respectively.

Oil futures tumbled more than 9% after news that OPEC would keep output unchanged. Crude oil for January delivery fell US$5.15, or 9.4%, to end at US$49.28 a barrel on the New York Mercantile Exchange.

Talisman Energy Inc. fell $2.14, or 17.2%, to $10.27 and Suncor Energy Inc. tumbled $4.70, or 16.4%, to $23.90.

Nexen Inc. was down $3.65, or 14.3%, to finish at $21.85 and EnCana Corp. slid $7.68, or 12.8% to $52.32.

Gold and other metals futures tumbled sharply on Monday. Gold for February delivery dropped US$42.20, or 5.15%, to end at US$776.80 an ounce on the New York Mercantile Exchange.

The sub-gold index dropped 13.8%.

Metals companies in the materials group took a hard hit Monday, including Barrick Gold Corp., down 13.4% to $32.65 and Goldcorp Inc., down 16.7% to $29.15.

Agnico-Eagle Mines Ltd. lost $8.62, or 17.7%, to end the day at $39.97.

Shares of Teck Cominco Ltd., which traded in huge volumes on Monday, plunged 17.33% to $4.96.

The financials group didn’t escape the damage on Monday, falling 8.4% by the day’s close.

Manulife Financial Corp. saw its shares drop $3.54, or 14.75%, to end at $20.46.

Royal Bank of Canada fell 8.66% to $39.44, and Toronto-Dominion Bank dropped 8.15% to $42.25.

Also lower was CIBC, down 7.6% to $46.09 and Power Corp., down 13.7% to $22.00.

Fairfax Financial Holdings Ltd. shares slipped 0.5% to $358.17 after it announced plans to purchase the remaining outstanding shares of Northbridge Financial Corp. for approximately $686 million.

Air Canada’s A-class shares fell 10.9% in Toronto trading after Groupe Aeroplan Inc., which runs its frequent-flier program, agreed to make an accelerated payment of $70 million for reward tickets to help the airline boost liquidity. The shares closed at $1.96.

Shares of BCE Inc. slid another 7.6% to close at $23.06.

The S&P/TSX Venture composite index shed 27.23 points, or 3.55% to end at 739.12.

The Canadian dollar surrendered half a cent against the U.S. dollar, closing at US80.31¢.

Stock markets south of the border didn’t fare any better, after the National Bureau of Economic Research said the U.S. economy has been in recession for about a year.

A late-day sell-off sent all three main indexes down sharply in the last hour of trading.

The Dow Jones industrial average fell 679.95 points, or 7.7% to close at 8,149.09.

The Nasdaq composite finished the day at 1,398.07, down 137.5 points or 9%, and the S&P 500 moved down by 80.03 points, or 8.9%, to end at 816.2.

IE