Former billionaire investor Sung Kook “Bill” Hwang was sentenced to 18 years in prison on Wednesday over the collapse of Archegos Capital Management, which cost Wall Street banks more than $10bn. Hwang was sentenced by US district judge Alvin Hellerstein in Manhattan, where a jury convicted Hwang in July on 10 criminal charges including wire fraud, securities fraud and market manipulation. Archegos’s March 2021 implosion took less than a week, stunning Wall Street and Hwang’s lenders. The US attorney’s office in Manhattan sought a 21-year prison term for Hwang – unusually long for a white-collar case – and for him to forfeit $12.35bn and make restitution to victims. “It stands among a rare class of cases that truly could be described as a national calamity,” prosecutor Andrew Thomas said at the sentencing hearing before Hellerstein. Hwang, 60, set up Archegos in New York as a family office in 2013, the year after his former hedge fund, Tiger Asia Management, pleaded guilty to wire fraud in an insider-trading case. Prosecutors accused Hwang of lying to banks about Archegos’s portfolio so he could borrow money aggressively and make concentrated bets on media and technology stocks such as ViacomCBS, now called Paramount Global. While Archegos eventually managed $36bn, Hwang’s borrowing helped him amass $160bn of exposure to stocks. His downfall occurred when Hwang was unable to meet margin calls, as the prices of some of his favorite stocks began falling and various banks unloaded stocks that had backed his so-called total return swaps. More than $100bn of market value in Hwang’s stocks was wiped out. Several banks suffered losses, including Credit Suisse, which lost $5.5bn, and Nomura Holdings. Credit Suisse is now part of UBS. Hwang’s lawyers’ request for no punishment also cited Hwang’s Christian faith and his non-profit Grace and Mercy Foundation, which has since 2006 donated at least $600m to combat homelessness, poverty and human trafficking, among other causes. Hwang’s lawyers have said his net worth has fallen to “at most” $55.3m.