Absolutely rock-solid? Investors don't think so.
An internal memo written by the chief executive of Deutsche Bank, intended to reassure, has had the reverse effect.
The bank's share price fell further, the cost of insuring its debt against default rose.
The cause of all the anxiety is Deutsche Bank's contingent convertible bonds or "cocos". They are essentially loans that are designed to transform into bank shares in cases of emergency.
Cocos were dreamed-up as a way of avoiding investor panic, in this instance they appear to be causing it.
Although if creditors end-up holding a stake in Deutsche Bank they don't want, they can't say they weren't warned.
The wider worry is that Deutsche Bank isn't an outlier; that the downturn in emerging markets has left the whole banking sector over-stretched.
That anxiety looks overdone. At the end of last year the The Bank of England stress-tested Britain's biggest banks to establish if they were strong enough to cope with a severe economic shock.
The "disaster" scenario envisaged a slump in oil prices and a slowdown in China and the Eurozone far worse than anything we've seen to-date.
All seven lenders passed. The ECB carried out similar tests on its banks.
While some investors have seen enough and are selling up others are holding firm. Aviva Investors is one of them.
One fifth of people in retirement in Britain have some form of pension with Aviva Investors.
Peter Fitzgerald's team manages £85 billion of clients' money.
He experienced the panic of the financial crisis in 2008 first-hand and feels strongly that the fear has been "over-exaggerated". In his view there won't be a banking crisis or even a recession.
On Wall Street tonight the markets closed flat as a Shrove Tuesday pancake.
Calm restored. For now.