Art Cashin says he'll be watching carefully to see if the market forces interest rates higher at a faster rate than the Federal Reserve wants.

Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani around midday "that will be a very key focal point ... in the beginning of the coming year — to see if the bond market decides to tamper, if you would, with the tapering by accelerating or moving rates in a manner that the Fed is not ready for."