How one of world's greatest hidden fortunes was wiped out in days

US billionaire Bill Hwang and his private investment firm, Archegos Capital Management, are at the centre of one of the biggest margin calls of all time.

From his perch high above Midtown Manhattan, just across from Carnegie Hall, Bill Hwang was quietly building one of the world’s greatest fortunes.

Even on Wall Street, few ever noticed him -- until suddenly, everyone did.

Hwang and his private investment firm, Archegos Capital Management, are now at the center of one of the biggest margin calls of all time--a multibillion-dollar fiasco involving secretive market bets that were dangerously leveraged and unwound in a blink.

Hwang’s most recent ascent can be pieced together from stocks dumped by banks in recent days--ViacomCBS Inc., Discovery Inc. GSX Techedu Inc., Baidu Inc.--all of