Art Cashin says "we're clearly overbought" after "one heck of a run" that's put stocks well above their 200-day moving average.
But Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani around midday there are some "year-end dynamics" still supporting equities.
"People are wondering if there's going to be a lot of preloading of 401(k)s and pension funds. 2013 started out ... with an absolute bang because of that. People loaded up on the first couple of days, so we'll wait and see if that continues here."
For now, Cashin says stocks have had a "heck of a performance and the bulls have nothing to be ashamed of."