The Family Office That Took Down Credit Suisse

In March 2021, a family office named Archegos Capital Management — managing approximately ten billion dollars of personal wealth on behalf of its sole principal, Bill Hwang — defaulted on margin calls totaling tens of billions of dollars. The defaults, processed across multiple prime brokers including Credit Suisse, Nomura, Morgan Stanley, Goldman Sachs, and UBS, ultimately produced cumulative bank losses estimated at over ten billion dollars. Credit Suisse alone reported losses of approximately five and a half billion dollars from the Archegos position. The collapse contributed materially to Credit Suisse's eventual sale to UBS two years later.

Hwang, a former Tiger Asia hedge fund manager who had previously settled an SEC insider-trading case, had built Archegos's positions through total-return swaps — derivative contracts that allowed him to obtain economic exposure to publicly traded stocks without appearing on shareholder registries. The swap structure permitted Hwang to accumulate concentrated positions in companies including ViacomCBS, Discovery, GSX Techedu, Tencent Music, and Vipshop without triggering disclosure requirements that would have alerted the market — or each prime broker — to the cumulative size of his exposure.

The Hidden Concentration. The structural problem was that no single prime broker knew the total size of Hwang's positions across the others. Each broker saw only its own exposure. Cumulatively, Hwang had reportedly built leveraged positions of forty to ninety billion dollars in underlying notional exposure against ten billion dollars of equity. The leverage ratio implied that a relatively modest decline in the underlying stocks would consume the entire equity cushion and produce margin calls the family office could not meet.

The Trigger. In late March 2021, ViacomCBS announced a secondary share offering that pressured the stock. The decline cascaded through the highly leveraged positions. Margin calls were issued. Hwang could not meet them. The prime brokers, discovering simultaneously the magnitude of cumulative exposure across the industry, attempted to unwind their positions in parallel. The selling pressure of multiple ten-billion-dollar block trades hitting the market within hours produced a roughly thirty to fifty percent decline in the affected stocks. The brokers who unwound first lost less; those who unwound later lost more.

The Reckoning. Credit Suisse, which had been slower to act than competitors, absorbed the largest single loss. The bank's wealth-management business, already under pressure from a separate scandal involving the collapse of Greensill Capital, lost client confidence. Within two years, Credit Suisse had been acquired by UBS in a Swiss government-brokered emergency transaction. Bill Hwang was charged criminally with securities fraud and racketeering in 2022 and convicted in 2024.

The Archegos collapse exposed structural weaknesses in the prime brokerage business that regulators have, since, attempted to address — including expanded disclosure requirements for derivative positions and tighter cross-firm exposure monitoring. The reforms remain partial. The lesson, that concentrated leveraged positions in publicly traded equity can be hidden across multiple counterparties until they collapse simultaneously, has been printed in capital-markets memory. The next time will, presumably, take a different form. The systematic incentive to hide leverage from regulators and brokers has not changed.