Construction company MasTec (NYSE: MTZ) is making a big bet on clean energy and infrastructure, agreeing to buy Infrastructure & Energy Alternatives (IEA) (NASDAQ: IEA) for $1.1 billion in cash and stock. Investors in the two companies had mixed reactions, with shares of IEA up nearly 30% and shares of MasTec down 10% in Monday morning trading. MasTec is a construction and engineering company that has long had ties to the energy industry, working on some of the largest oil and gas, power generation, and power delivery projects around the world.