Britain's opposition Labour leader Jeremy Corbyn told Morgan Stanley that bankers are right to regard him as a threat because he wants to transform what he cast as a rigged economy that profited speculators at the expense of ordinary people.
Morgan Stanley last month warned that political uncertainty in Britain was a bigger threat than Brexit for some domestic investors given the risk of Corbyn winning power and radically changing Britain's free-market economy.
"Bankers like Morgan Stanley should not run our country but they think they do," Corbyn, a 68-year-old socialist, said in a video posted on Twitter.
"So when they say we're a threat, they're right: We're a threat to a damaging and failed system that is rigged for the few," he said.
Since Prime Minister Theresa May's botched gamble on a June snap election lost her party its majority in parliament, some investors and many of Corbyn's political opponents now see him as a potential prime minister if May's government falls.
Corbyn has cast bankers as the villains behind the 2008 financial crisis and promised to increase taxes on the banks and investment funds which trade out of London, the only financial capital to rival New York.
Corbyn said banks like Morgan Stanley were speculators.
"These are the same speculators and gamblers who crashed our economy in 2008 and then we had to bail them out," Corbyn said. "Their greed plunged the world into crisis and we are still paying the price."
Corbyn's manifesto promising renationalization, higher public spending and tax rises for the rich won him 40 percent of the votes cast while May's Conservatives won 42 percent.