The S&P 500 broke below an important trend line Monday, and technicians see more selling ahead.
"I'm not willing to say this is a bear market at all. I just think you're going to have a very severe, very sustainable and really quite ugly correction that will probably make a lot of people wail and gnash their teeth before it's done," said Dennis Gartman, publisher of the Gartman Letter. Gartman said on "Fast Money" that he is neutral on stocks, after getting concerned about the market a week ago, and he sees a total 15 percent correction for the S&P 500.
The S&P 500 is down 5.7 percent since the start of the year, and it fell 2.3 percent Monday. The S&P ended the day at 1741, and selling accelerated when it broke through 1770, a level it tested and held last week.