Fast cars and fast money make a terrible combination. Mix in a banking crisis, an attempted takeover of Volkswagen and several billion euros of share options and you also get German takeover rules in urgent need of change. Although Porsche is not the only company to use cash-settled call options to buy a German rival by stealth – car parts maker Schaeffler recently did the same – it has done so with more spectacular effect than anyone else.

The mechanics surrounding Porsche’s attempts to buy VW are obscure because its option positions need not be disclosed. But the wheeling-dealing goes something like this: to increase its 35 per cent stake above 50 per cent, Porsche bought options over much of VW’s freefloat. The banks that sold these options meanwhile hedged their exposure by buying VW shares. Hedge funds, drawn by VW’s pumped-up valuation – 24 times forecast earnings, eight times as high as the sector average – then shorted VW as fast they could.