As an example in the case of Lehman Brothers their bankruptcy didn’t affect retail customers who were protected by the SIPC and whose investment accounts were q

As an example in the case of Lehman Brothers their bankruptcy didn’t affect retail customers who were protected by the SIPC and whose investment accounts were quickly move to other brokerages. But it’s not always so sanguine. To find a bankruptcy with commingled prop and customer funds you need only look to MF Global. To find a retail brokerage bankruptcy with commingled funds you can go “Wolf of Wall Street” and look at Stratton Oakmont. And despite how smooth everything turned out for Lehman there was a period of a day or two for some retail guys where it wasn’t exactly clear where your money was.