But some stocks haven't felt that bullishness. The three biggest losers in the index at the halfway point of the year are Deckers Outdoor (DECK 2.20%), Enphase Energy (ENPH 3.13%), and UnitedHealth Group (UNH 4.46%). Here's a look at how much these stocks were down as of the end of June, why they've been struggling, and whether they're good buys right now. Deckers Outdoor: Down 49% in the first half of 2025 Despite generating decent growth numbers this year, footwear company Deckers Outdoor is the S&P 500's ...