Banks’ back-office margin systems buckled under the sheer weight of trading volumes seen during the coronavirus market rout, resulting in missed margin payments and give-up trades being left on the books of executing brokers.

A combination of processing backlogs and manual errors meant some clearing brokers were left with uncollateralised overnight exposure to buy-side clients, while others had to meet surprise margin calls at a time of funding stress.

Five sources cited problems with systems