The worldwide decline in the value of banking shares and the constant whispers about their stability is unsettling. especially with banks. In that sector there is no smoke without fire. Just now it is not clear whether we see smoke or steam.
Banks are safer than they were pre-crash, but that judgement must be tempered by the nature and size of the crash. Last time it was dodgy property funding in the US that set the overheated system ablaze. This time there is an oil price crash, a slowing of Chinese demand which is having a dangerous knock-on effect in the East. But there is a new danger. The Chinese economy is internally over borrowed, especially in property speculation. There appear to be new cities even, with few people in them. All this has been funded by borrowing.
The Yuan is under speculative attack, which the Chinese government has tried to stem by eye popping use of its vast cash reserves, now down by 25%. If you worry about banks, you must hope it works. For the sub-prime China style is that all the properties and businesses in debt are valued in Yuan, but much of the borrowing is in dollars. If Chinese firms go under, Chinese banks will be in trouble. And in the global economy all banks are linked. Even if China saves its own, the damage to confidence is done. One thing can lead to another.