More than half (24) have posted positive total returns since going public. Nationstar Mortgage LLC is reporting the largest gain. It is one of three PE-backed business that has seen its share price more than double from its IPO price. The other two are by Annie’s Inc. and Five Below Inc. Bringing up the rear in this year’s crop is Ceres Inc., which went public in February, trading at 58.62 percent below its IPO price.