The S&P/TSX composite index dropped 235.64 points to 14,312.07, led by falling resource stocks as prices for oil hit a two-year low.
Losses picked up at mid-morning when reports surfaced that a gunman had opened fire at the National War Memorial in Ottawa, fatally wounding a soldier, then moved to nearby Parliament Hill and wounded a security guard before the attacker was himself shot dead. A manhunt was still underway in the national capital, with reports there may have been as many as three gunmen.
However, analysts thought that while there may have been a short, knee-jerk reaction to the shootings, the declines on the TSX had everything to do with markets stepping back after a recent big move upward.
"The market was trading down at the open, it was already in that trend, so the decline was to be expected," said Michael Greenberg, portfolio manager at Franklin Templeton Solutions Group
The Canadian dollar was down 0.12 of a cent at 88.94 cents US as the Bank of Canada announced that it was leaving its key rate unchanged at one per cent. In its monetary policy report, released at the same time as the rate announcement, the bank adjusted the economic growth prediction it made in July, nudging it up one-tenth of a point to 2.3 per cent for 2014.
Traders also took in a worse than expected reading on mid-summer Canadian retail sales. Statistics Canada reported retail sales fell 0.3 per cent overall in August. Economists had expected a flat reading.
U.S. indexes also gave up ground after a string of sharp run-ups, with the Dow Jones industrials down 153.49 points at 16,461.32, the Nasdaq falling 36.63 points to 4,382.85 and the S&P 500 index giving back 14.17 points to 1,927.11.
The TSX had gained almost 700 points over the previous four sessions in a rebound that followed a big sell-off in markets triggered in part by worries about the global economy. The TSX is down seven per cent from the record highs set in early September, although still ahead six per cent year to date.
Investors have also been concerned about the impending end to the U.S. Federal Reserve's key stimulus program involving the purchase of hundreds of billions of dollars of bonds.
Analysts have been careful to warn that it's too early to sound the all-clear on the current retracement and that volatility will be a fixture on markets for a while yet.
"And volatility is not necessarily a bad thing, it’s a natural thing for markets," Greenberg said.
In earnings news, Canadian National Railway (TSX:CNR) posted net income of $853 million, up 21 per cent from a year earlier. Revenues grew 16 per cent to a record $2.7 billion but adjusted earnings came in at $1.04, a penny short of expectations and its shares dipped 50 cents to $75.18.
The energy sector led TSX decliners with a 3.3 per cent slide as the December crude contract in New York dropped $1.97 to US$80.52 a barrel, oil’s lowest settlement since June 28, 2012. The plunge came amid downward pressure on the euro, which drove up the value of the U.S. dollar. Commodities are priced in greenbacks. Also, data showed crude supplies rose by 7.1 million barrels last week, about three times more than expected.
The base metals sector declined three per cent as December copper faded a penny to US$3.02 a pound.
The gold sector about three fell per cent while December bullion faded $6.20 to US$1,245.10 an ounce.
Financials were also a major drag, falling 1.1 per cent.