North American markets on Wednesday endured a session of sharp losses that ended two days of gains.

Pulled down by falling commodity prices, the S&P/TSX composite index shed 235.22 points to close at 11,585.87

The Dow Jones industrial average tumbled 179.79 points to 11,010.90, while the Nasdaq composite index dropped 55.25 points, finishing at 2,491.58.

More worries about Greece also weighed on stocks. German Chancellor Angela Merkel said that a bailout package for Greece might have to be renegotiated.

Fear of a Greek default and its potential impact on the economy contributed to large equity losses last week.

However, markets reversed course earlier this week as optimism grew that a solution to the Greek debt problem appeared to be in the works. The TSX added more than 350 points before giving back part of that on Wednesday.

Commodities retreated on renewed worries of an economic slowdown.

The price of light sweet crude for November delivery fell $3.24 to close at $81.21 US a barrel.

The Canadian dollar, which is closely tied to the rise and fall of the price of oil, ended at 96.84 cents US, down 1.16 cents on the day.

Gold for December delivery closed at $1,618 US an ounce, down $34.40 an ounce from Tuesday's settlement price.

"What ends up happening here is you hear rumours and the market is acting on rumours," said Allan Small, senior investment adviser at Dundee Wealth.

"What I'm telling my clients at this juncture is, stay in the market since the alternatives to the market is 1.5 to two per cent on a government bond or GIC. Stay defensive, there are a lot of good dividend players out there."

With files from The Canadian Press