** Shares of U.S. infrastructure contractor Primoris Services Corp PRIM.N plunge 36% to $71 premarket

** If losses hold through open, stock to hit more than one-year low

** Co cut full-year profit forecast and announced COO Jeremy Kinch's departure on Monday

** Co now expects adjusted EPS between $2.05 and $2.60 vs the prior $4.80 to $5.00 range

** Expects lower revenue and gross profit for full-year in its renewables business

** Brokerage Keybanc downgrades stock rating to 'sector weight' from 'overweight', says repeated guidance cuts indicate slow recovery in valuation

** Cut in renewables business revenue estimate to $2.1 billion reflecting project delays, with the biggest earnings hit expected in Q2 - Keybanc

** On an average, 10 brokerages rate the stock "buy" or higher

** Up to last close, stock down 12.7% YTD