Traditional, strategic investors, like E. & J. Gallo Winery, Jackson Family Wines and The Wine Group are active in the United States’ winery and vineyard mergers and acquisitions market, as are international wine players, such as Pernod Ricard and Concha y Toro. But a third group of investors in the wine space, private equity firms, are making efforts to build wine portfolios—if the investment is right. In 2015, J.W. Childs Associates (now Prospect Hill Growth Partners) became...