How did currency trader John Rusnak hide $691 million in losses before being caught for bank fraud?

John Rusnak was bullish on the yen. He believed the yen had taken all the damage it could following the bursting of the Japanese bubble. Further, Rusnak believed the yen would appreciate consistently against the dollar. Under these conditions, a trader normally would buy forward contracts to get yen for cheaper than market value, while hedging the position with a combination of put and call options. In practice, Rusnak was so bullish on the yen that he neglected to hedge his forward contracts. His luck held, however, until a series of policy changes in Asia culminated in crisis on the Asian market and prompted a long slide in the value of the yen and other Asian currencies.

With his unhedged positions facing losses, Rusnak panicked. He entered false options into the system that made it look like his positions were hedged. While the options kept the bank from discovering the losses, he set about doubling his bets on the rise of the yen. Rusnak convinced his superiors that a prime brokerage account would allow him to wring higher profits from the growing currency operations. Prime brokerage accounts generally are given to hedge funds and high profile traders with a lot of capital to play with. However, Rusnak was granted the account despite the fact that, unbeknownst to his superiors, he already was working in the red.

With his new account, Rusnak increased the size of his trades and kept his losses hidden by using options and a higher level forex contract called a historical rate rollover. This allowed him to hold off realizing his losses, while still betting more on the yen. It also meant that the total value of the forex operations at Allfirst was increasing. Even though the losses were barely detectable, the increasing amount of capital being tied up in the currency market was obvious. When the bank demanded that Rusnak release some of the capital to ease its balance sheet of the heavy skew towards the forex market, the house of cards came tumbling down.