TORONTO (Bloomberg) - Canadian stocks fell, heading toward their first weekly decline since September 10, as Shaw Communications Inc. missed profit forecasts and an index of banks dropped the most in a month.

Royal Bank of Canada, the biggest Canadian company by market value, lost 1.7 percent from Thursday's unadjusted close, trading for the first time without the right to a 50 cent dividend. Shaw, Canada's largest cable and satellite television provider, decreased 4.2 percent after reporting earnings that missed the average analyst estimate by 17 percent.

Base-metals producer Lundin Mining Corp. climbed 8.7 percent after the Democratic Republic of Congo confirmed a joint venture's mining contract.

The Standard & Poor's/TSX Composite Index slipped 17.87 points, or 0.1 percent, to 12,581.36 as of 12.18 p.m. in Toronto. The index has slipped 0.2 percent this week after climbing 4.2 percent from September 10 through October 15.

"Because a parabolic rise will generally lead to a major crash, having things level off or retreat slightly, it's indicative of a healthier market as opposed to an irrational market," said Steven Conville, who helps manage C$8 billion ($7.94 billion) at Macquarie Private Wealth Inc. in Markham, Ontario.

The S&P/TSX's streak of five-straight weekly gains is the longest since April 2009.

The Thomson Reuters/Jefferies CRB Commodity Price Index has surged 7.4 percent during the period through yesterday as the US dollar has declined on speculation central-bank stimulus measures will weaken the currency.

The S&P/TSX Banks Index dropped one percent two days after almost touching a three-year high in price per dollar of estimated profit.

"Canadian financials are right at valuation, and I mean not a dollar higher would be justified at this time," Mr. Conville said. "I don't care how many times they've increased their dividend or how good their balance sheet is, you can't tell me banks are healthier than they were in 2005."

Royal Bank declined 0.8 percent to C$55.84, adjusted for the dividend. Bank of Nova Scotia, Canada's third-largest lender by assets, lost 1.1 percent to C$54.71. Canadian Imperial Bank of Commerce, the No.5 bank, decreased 1.2 percent to C$78.37.

Shaw retreated 4.2 percent to C$22.46 after saying it earned 28 cents a share excluding some items in the fourth quarter, trailing the average analyst estimate by 17 percent, the most since at least 2005.