Financial problems at the maker of spark plugs, wiper blades, brake calipers, brake shoes, tow hitches and motor oil has caused intense anxiety on Wall Street in recent weeks.

Car parts are not usually something that causes finance chiefs to lose much sleep. But the potentially multi-billion dollar financial crisis surrounding First Brands has them rattled.

As ever in finance, it’s what investors don’t know that scares the most, and with First Brands, there appears to be plenty.