(Bloomberg) -- In an era of prosperity for investment banks, Credit Suisse Group AG is careening from one crisis to another and then another -- this time, with a $4.7 billion writedown tied to billionaire investor Bill Hwang’s trading blowout.The staggering hit -- the largest yet linked to market-shaking losses run up by Hwang’s Archegos Capital Management -- prompted sweeping management changes at the Swiss bank Tuesday and cast fresh doubt on its checkered record of managing risks.