Steve Leuthold, a star money manager who earned big money shorting stocks last year, is now a raging bull.

In April, he predicted the Standard & Poor’s 500 Index would reach 1,100 by year-end, a 22 percent gain from Wednesday’s close. Now he thinks the index can reach that level sooner.

“When I said 1,100, people thought I was smoking something,” Leuthold told Bloomberg TV.

“Now it seems like a much more rational thing, and we are seeing many … people that have said, ‘Hey, I’m going to wait until next year when the economy is improving,’ that are now saying, ‘Uh oh, I think we maybe better move before that.’”

Leuthold says he’s likely to raise the equity holdings in his core fund to a 70 percent weighting in the next month, up from 65 percent currently and 50 percent a few months ago.

Seventy percent is his maximum.

“The market by our work is still somewhat undervalued,” Leuthold says.

“And I think what is going to really get a push going here for the market — and June could be pretty impressive — is that a lot of big institutions are underinvested … below their normal guidelines.”

Bottom line: “I think you’re going to see a number of firms that are … under their benchmarks that are going to be moving toward it.”

Leuthold isn’t the only bull.

Robert Doll, BlackRock’s global chief stock investment officer, sees the S&P hitting 1,000 by year-end.