"I thought it was a good buy point two weeks ago Wednesday and so we bought some," Gundlach told Reuters. Gundlach, who oversees $90 billion in assets for the Los Angeles-based DoubleLine, said the firm was at "maximum underweight" since last August.

The Standard & Poor's 500 Index was down more than 5 percent in January alone and added to losses by mid-February. The index was off 10.5 percent year-to-date by Feb. 11.

In early February, Gundlach had said that stocks were in a bear market.

"We were near a minimum allocation to stocks before the summer meltdown," Gundlach said. "We stayed there while the SPX dropped over 250 points. Yes, stocks are, in our view, in a bear market, but there are counter-trend moves along the way."

Gundlach said the conditions in the second week of February with "wickedly negative equity sentiment were such that risk/reward favored a potential tradable rally and also made such a low allocation less advisable."

He added: "If we were not allowed to trade for two years and had to keep a static portfolio, we would not have bought two weeks ago. But that is not our situation. As long as you are less in the market in sell-offs than you are in rallies, you will outperform. As long as you are longer than the market in rallies than you are in sell-offs, you will outperform."

He also said oil will "really easily" rally toward $40 a barrel as the price has dropped so much. U.S. crude oil settled at $32.78 on Friday. Last year, Gundlach correctly predicted that oil prices would plunge, junk bonds would live up to their name and China's slowing economy would pressure emerging markets. In 2014, Gundlach also correctly forecast U.S. Treasury yields would fall, not rise as many others had expected.

Gundlach said the Shanghai Composite, which is trading around 2,767 points, is set to fall to around 2,500.