Investment banking has always been a highly cyclical business, growing when the markets grow, shrinking when they shrink. But a combination of regulation, technology and investment suggests that, as stockbrokers have traditionally whispered in boom times, this time it’s different. The go-go era of investment banking that began in the mid-1980s and thrived up to the financial crisis appears to be on its way out, as the biggest banks shrink in response to regulation and smaller, more focused firms, funds and start-ups take a larger share of the market. It’s becoming a mature industry. So what is set to change on Wall Street then?