Lloyds Banking Group's wholesale banking division suffered several hours of downtime in its trading system as a server cooling system failed and traders were forced to revert to pen and paper and telephones during a day of turmoil in the stock market.
"We experienced an interruption in the early hours of [4 August] to our trading technology system, which provides services to our corporate customers," said a bank spokesman. "The system was back up and running within a few hours."
The downtime came during a busy day on the stock markets as billions of pounds were wiped off the value of shares.
The bank said the downtime did not stop business: "During the system outage, we were still open for business and undertaking trades for our customers, as well as managing our core functions, so the impact was minimal. Our relationship managers were in contact with our customers to ensure we met their needs."
The bank said there was no impact on its online banking for day-to-day business or retail banking customers.
According to a former investment banking CIO, who asked to remain anonymous, the downtime was probably more embarrassing than costly due to Lloyd's small presence in the investment sector.
"It is not that big for Lloyds because it is not a big player in that market," he said.
He said Lloyds' trading arm is really just executing investments for its corporate customers: "If a big investment bank had these problems it be a much bigger problem."