Watch Art Cashin: The real reason stocks are up

Cashin says: Have to get beyond weather excuse

Art Cashin said Thursday's stock gains that brought the benchmark S&P back near its all-time highs weren't sparked by the latest economic data.

Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani around midday, "The buying that I'm seeing here today doesn't look like big institutional buying. The feeling on the floor is that this up move that we're having may have a lot more to do with the option expiration week than it does with any of the economic data that came out."

He adds that the "viewers can cross their fingers because quite often there's kind of a Thursday-Friday combo on an option expiration week. "

Cashin believes that if the stock market can hold its Thursday gains, there's "better than a 50 percent chance" stocks could wind up closing higher on Friday as well.