If the average amount of weekly outflows is x billion, then the chances that outflows of this amount are so rare, that you would have to go 500 million weeks for this to happen.
Six degrees of Standard deviations is one of those things that should be the cause for pause.
> A 6-sigma event is extremely rare. If you want to put a number to it, think 1 in 500 million.
I think it isn’t. Just like “science” used to say that rogue waves were impossible, the driver for this phenomona will eventually be described.