When Michael Burry starts buying call options on a stock that has fallen 50 per cent from its highs, experienced investors take notice. Still, when Donald Trump’s portfolio simultaneously shows purchases of bonds from the same company, the coincidence becomes harder to ignore.

UnitedHealth Group has attracted both men’s attention just as America’s largest health insurer faces its worst crisis in decades. The stock has collapsed from over $600 to around $300 this year as medical costs surge faster than premium increases, forcing the company to slash profit forecasts and pull earnings guidance entirely.