iRobot Shows Just How Risky Investing in Mergers and Acquisitions Can Really Be

There's an investment tactic on Wall Street called merger arbitrage. It isn't meant to produce eye-catching home runs, instead focusing on getting a lot of reliable singles. On the surface, merger arbitrage seems like it would be easy, but iRobot (IRBT -2.60%) and Spirit Airlines (SAVE 8.54%) show it can be harder than it seems.Here's why you need to be careful buying into mergers and acquisitions, noting that United States Steel (X -0.15%) looks like it could be the next pain point for investors.There's no ...