Robert Rasmus and James Whipkey didn’t have a problem in July 2012; they had a wrinkle. The founders of private-equity firm Red Oak Capital Management had formed Hi-Crush Proppants LLC (HCLP), a producer of highly sought-after Northern White sand for hydraulic fracturing, in 2010. Hi-Crush was about to go public, and it had plenty of things going well for it: a rail line that bisected its Wyeville, Wisconsin, plant; plenty of the aforementioned sand; and long-term contracts that produced seemingly dependable income streams. Hi-Crush’s wrinkle was that it sought to ...