TORONTO (Bloomberg) - Canadian stocks fell for the first time in seven days after UBS AG cut its 2011 forecast for potash prices and natural gas declined on concern US stockpiles are too high.

Potash Corp. of Saskatchewan, the world's largest fertiliser producer, dropped 2.3 percent on the comments from UBS analyst Joe Dewhurst. EnCana Corp., Canada's largest natural gas producer, lost one percent as the fuel decreased 3.2 percent. Barrick Gold Corp., the world's largest gold producer, gained two percent as precious-metal futures climbed for a second day.

The Standard & Poor's/TSX Composite Index retreated 18.38 points, or 0.2 percent, to 11,927.59. The index was on the positive side the entire day, dropping below yesterday's close only in the final tick at 4.10 p.m.

The S&P/TSX rallied 4.3 percent during its streak of gains, which overlapped an eight-day run for the Reuters/Jefferies CRB Commodity Price Index.

Energy and raw-materials companies make up 46 percent of Canadian stocks by market value.

Canada's dollar had its first back- to-back weekly gains since April as rising oil prices and falling risk aversion enhanced the appeal of currencies from countries that rely on commodities for growth.

The Canadian currency rose to a one-month high today, extending its five-day advance to 1.1 percent as investors warmed to risk assets and speculated the nation's central bank will raise interest rates faster than other countries.

"The stronger performance over the week is partly on the return of risk appetite and, more importantly, oil rallying again and remaining above $75 a barrel," said Matthew Strauss, senior currency strategist at Royal Bank of Canada in Toronto.

The Canadian currency, nicknamed the loonie for the image of the waterfowl on the C$1 coin, appreciated 0.7 percent to C$1.0211 per US dollar at 4.18 p.m. in Toronto, from C$1.0282 yesterday. One Canadian dollar buys 97.95 US cents.

Three times this week the Canada's dollar had its first back- to-back weekly gains since April as rising oil prices and falling risk aversion enhanced the appeal of currencies from countries that rely on commodities for growth.

The Canadian currency rose to a one-month high today, extending its five-day advance to 1.1 percent as investors warmed to risk assets and speculated the nation's central bank will raise interest rates faster than other countries.