In fact, Leeson derivative contracts traded on the two markets which were in some cases and in other cases different values covered. For example, aids lack of supervision, Leeson has executed a strategy known as "straddle" (subduction) in order to make profit by selling put options and call on the same financial instrument, in this case, the Nikkei 225 index. A straddle operation generates gains when the market is stable but may produce disastrous losses if the market is volatile, a sharp contrast to the relatively conservative arbitrage that you have in mind for Barings operations of Leeson.