It's the penultimate day of the trading year, and that means investors should watch out for a delayed selling phenomenon, said Art Cashin, UBS director of NYSE floor operations.
"A lot of people assume that if you have a stock that's done very well this year, you want to postpone selling it until after the first of the year because that carries you a whole year ahead tax-wise," Cashin told CNBC's "Squawk on the Street" Wednesday. "With that in mind, these two days, we've seen in the last five years a phenomenon develop where people start shorting those stocks, figuring they will be weak at the beginning of next year."
Cashin said that part of the delayed selling pattern can be attributed to the levels of uncertainty surrounding the market this year. And while stocks generally perform well in January, that hasn't necessarily been the case over the past two years.