Art Cashin thinks Tuesday afternoon's stock action will be a "very important test" and "absolutely critical" to watch.
UBS' Cashin told CNBC's Bob Pisani the new money that came into the market at the beginning of August appears to be drying up and he wants to see if the market can keep moving higher despite that.
Speaking at midday, Cashin said, "We've come slightly off the lows. If people believe we've bottomed for the day, those who are waiting to get a bargain thrown into their basket may start to pay up."
If they do, Cashin thinks it would be a positive sign for stocks.