Bain Capital and The Carlyle Group have teamed up to buy German light bulb maker Osram Licht for $3.8 billion in a rare instance of private equity giants co-investing together. In the first half of 2019 there were 107 deals with more than one private equity investor, down 57% from the same period last year. One of the risks of private equity firms working together on a deal is that if a company's performance dips, deliberations about how to get business back on track can be frustrating and protracted.