Art Cashin says he's concerned there's too much optimism about more gains for stocks this year.
Cashin, UBS' director of floor operations at the NYSE, told CNBC's Bob Pisani around midafternoon that "the bulls are making the case we're up 25 percent on the year, and in most historical cases, you run even further in the final two months" with some people talking about the S&P hitting 1850. That would be a gain of another 5 percent.
Noting that the stock newsletters are very bullish right now, Cashin takes a contrarian view. "Not to dampen the parade, I think we want to keep an eye on frothiness here."