For many portfolio companies, the value is in the eye of their private equity owner. Just ask Southland Royalty, a US energy firm that filed for bankruptcy last week.

At the end of September last year, EnCap Investments, the private equity firm that owned Southland, valued its investment in the company at $773.7m, according to The Wall Street Journal. By the end of 2019, EnCap had written down the investment to zero, the WSJ reported.