TORONTO (Bloomberg) - Canadian stocks rose, reversing a weekly decline, after the US said growth slowed less than economists estimated and Federal Reserve Chairman Ben Bernanke said the Fed "will do all it can" to ensure recovery.

Royal Bank of Canada, the country's biggest lender, rebounded 2.7 percent after losing 3.4 percent yesterday. Canadian Natural Resources Ltd., the country's second-largest energy company by market value, gained 4.1 percent as oil futures advanced for a third day. BlackBerry maker Research In Motion Ltd. fell 2.1 percent as a potential ban on some messaging services in India drew nearer.

The Standard & Poor's/TSX Composite Index climbed 188.1 points, or 1.6 percent, to 11,841.28 at 2.03 p.m. in Toronto. For the week, the benchmark has gained one percent.

"We're dealing with a very, very fragile psychological market," said Gerry Brockelsby, who helps oversee C$125 million ($118 million) as a money manager at Marquest Asset Management Inc. in Toronto. "Everyone overreacts to small changes in expectations."

The S&P/TSX slipped 0.5 percent this month through yesterday as data on US unemployment, housing and manufacturing indicated a slowdown in the recovery in Canada's largest trading partner. Smaller-than-estimated profit reports from Bank of Montreal and Royal Bank this week partially offset the impact of BHP Billiton Ltd.'s $39 billion takeover offer for Potash Corp. of Saskatchewan Inc., which became public on August 17.

US gross domestic product grew at a 1.6 percent rate in the second quarter, the Commerce Department said yesterday in Washington, a revision from a 2.4 percent estimate issued last month. Economists had forecast the department would lower the figure to 1.4 percent, according to the median estimate in a Bloomberg survey.

Bernanke told a central bankers' symposium in Wyoming that the Federal Reserve "is prepared to provide additional monetary accommodation through unconventional measures if it proves necessary, especially if the outlook were to deteriorate".

The six largest publicly traded Canadian banks all rose. Royal Bank, which got 26 percent of its revenue from the US last year, gained 2.7 percent from a 13-month low to C$50.27. Toronto-Dominion Bank, which has 1,043 US branches, advanced 3.4 percent to C$71.35. Bank of Nova Scotia, Canada's third- largest lender by assets, increased 2.3 percent to C$51.66.

S&P/TSX energy stocks climbed for a third day as oil futures surged after Bernanke's speech.

Canadian Natural rose 4.1 percent to C$34.30. Cenovus Energy Inc., Canada's No.7 company in the industry by market value, advanced 4.2 percent to C$27.87. EnCana Corp., the country's largest natural gas producer, rallied 3.3 percent to C$29.21.

Teck Resources Ltd., Canada's largest base-metals and coal producer, climbed 3.7 percent to C$34.79 as copper headed toward its biggest two-day gain in a month. Ivanhoe Mines Ltd., which is developing copper and gold deposits in Mongolia with Rio Tinto Group, rose 3.1 percent to C$18.21.