One of the private investments Matt Cornue makes on behalf of a wealthy California family is in a specialty asset-management firm that buys tax liens on delinquent properties. 

That firm, Ram Financial Group, provides municipalities with cash to run public services, and in return receives fees and interest penalties owed on the lien until the homeowner’s taxes are current. The cash flows through to investors until the fund liquidates, unlike most private-equity funds, which lock up investor cash for up to 10 years until the companies it owns are sold or go public.