DoubleLine's Gundlach: Expect 'another wave down'

``"The reason the markets aren't going lower is people are holding and hoping," Gundlach said in a telephone interview with Reuters. "The market bottoms out when people are selling and sold out -- not when they are holding and hoping. I don't think you've seen real selling in risk assets broadly. Markets need buying to go up and they need volume to go up.They can fall just on gravity."''