Leeson's trading activities mainly involved three futures markets: Futures on the Japanese
Nikkei 225 stock index, futures on 10-year Japanese Government bonds (JGB futures)
and Euroyen futures. These products are all traded simultaneously and in similar design
on SIMEX and on a Japanese exchange. Leeson's main assignment was to arbitrage
between SIMEX and the exchanges in Japan and try to capitalize on small price
differences between the futures contracts. In reality, however, he was taking massive
speculative positions, financing SIMEX’ margin requirements by selling options and
borrowing huge amounts of money from Barings’ head office in London. By the end of
February 1995, the losses had become too large and Barings bank went bankrupt.