Renowned short seller Carson Block’s mauling of UK-listed NMC Health on Tuesday sent the company’s stock down as much as 32% in a single session. It also shed light on a fast-growing but opaque financing technique known as reverse factoring that has recently come under pressure from accountants, regulators and ratings companies.

The report from Block’s Muddy Waters Research cited a raft of alleged accounting ailments at the Emirati-based healthcare company, including that it overpaid for investments, “materially overstated” cash balances, and reported profit margins that “seem too good to be true”.