* C$ falls more than a penny from session high
* Bond prices mixed across curve
* G20 finance and central bankers weekend meeting in focus (Adds details)
TORONTO, Oct 21 (Reuters) - The Canadian dollar was lower against a rebounding U.S. currency on Thursday afternoon, reversing earlier gains as appetite for risk faded on stock markets and commodity prices fell.
Earlier, the currency had a firmer tone against its U.S. counterpart as world stocks and U.S. equity futures ticked higher and the U.S. dollar came under broad selling pressure.
But Toronto's main stock index was lower at midafternoon, as were U.S. stock indexes. The price of oil, often a driver of the Canadian dollar, was off nearly 3 percent around $80 a barrel.
The U.S. dollar, meanwhile, was able to rebound as doubts arose about how far-reaching any stimulus measures brought in by the U.S. Federal Reserve might be.
Investor focus was on the Friday and Saturday meeting of Group of 20 finance and central bank chiefs in South Korea. It is expected to try to reach agreement on a common path to manage currency, trade and macroeconomic imbalances.
"The volatility speaks to the friction that exists in the marketplace," said Jack Spitz, managing director of foreign exchange at National Bank Financial. "That friction is not limited to traders but also held by central bankers themselves. As they meet this weekend to discuss the potential for currency accord, the market itself is still undecided as to whether any success is going to be derived.
"That uncertainty is playing out with respect to the volatility being seen in the currencies."
At 2 p.m. (1800 GMT), the Canadian dollar CAD=D4 stood at C$1.0299 to the U.S. dollar, or 97.10 U.S. cents, falling more than a penny from its earlier high at 98.36 U.S. cents, and well off Wednesday's finish at C$1.0222 to the U.S. dollar, or 97.83 U.S. cents.
Canadian bond prices were mixed across the curve. The two-year bond CA2YT=RR was down 3 Canadian cents to yield 1.391 percent, while the 10-year bond CA10YT=RR gained 22 Canadian cents to yield 2.737 percent. (Reporting by Ka Yan Ng; editing by Peter Galloway)