US stocks could slump to their worst levels of the current bear market if the US economy falls into its sharpest recession in more than a decade, according to economist Nouriel Roubini. 

Dubbed "Dr. Doom" for his often ominous outlook, the New York University economics professor told Bloomberg in a broadcast interview Wednesday that the US economy is unlikely to dodge a recession as the Federal Reserve raises interest rates during a time of soaring inflation levels alongside a disgraceful unemployment rate. 

Roubini said the S&P 500 typically declines by 30% from peak to trough in times of short and shallow recessions. The broad-equity index slumped by 50% during the 2008 Global Financial Crisis, he noted. 

"So even if we had a mild recession, right now, the market is down, depending on the day, 15% from the peak, you'll have another 15% leg down," he said. "If we have something more severe than a short and shallow recession, but not as severe as GFC …. you have another 25% downside potentially in the markets." 

US gross domestic product declined 4.3% from its peak in the fourth quarter of 2007 to its trough in the second quarter of 2009, the deepest recession since World War II, according to the Federal Reserve. 

Warnings from major banks and CEOs about recession and stock-market losses for 2023 were prevalent as 2022 comes to an end, and the Federal Reserve plans its last rate hike of the year. JPMorgan CEO Jamie Dimon this week said with inflation "eroding everything" and consumer savings drawing lower, the economy looks poised to run into a mild to hard recession. 

"Sometimes, of course, there are false alarms," said Roubini. "But I think that the most important thing is that in the last 60 years, there's never been a case in US history that you have inflation above 5 percent - right now 7.7 - unemployment below 5 percent – now 3.7 – that when the Fed starts to raise interest rates, you get a soft landing. You get in every case a hard landing," he said. 

Roubini also expects to see stress in credit markets if the US were to enter a recession, with pressure on "lots of institutions like corporates, households, businesses that are highly leveraged."