Regulators like to bray about the dangers of systemic financial risk, but they seem not to care when they’re the source of the risk. Consider the US assault on Deutsche Bank that has tanked European bank shares this week.

The German bank's share price has fallen as much as 20% since a September 15 report in The Wall Street Journal that the US Justice Department is seeking a fine of up to $14 billion for selling mortgage-backed securities between 2005 and 2007. That is well beyond Deutsche Bank's ability to pay, given its $18 billion market capitalisation before the story broke.