DOUG JONES WAS just two years into his first startup when he got a cold call from Kevin Prokop, co-founder and managing partner of Detroit-based private equity firm Rockbridge Growth Equity. Jones’s content marketing company, Abuv Media, helped online universities identify prospective students, and its more than 50 percent year-over-year growth since it was launched in 2012 had caught Prokop’s attention.
Rockbridge had begun as