U.K. banks must reassess how quickly they could monetise their assets in the event of a crisis under new rules proposed by the Bank of England’s regulatory body, the Prudential Regulation Authority (PRA). The proposals are the first changes to the liquidity rules since these were updated in the aftermath of the 2008 financial crisis.

Ruth Prickett graduated from Cambridge University with a BA hons in History and has specialized in business and finance journalism for the past 20 years. She was editor of Financial Management, the magazine...