Well there must be some futures traders somewhere in the world who made a killing that day in the CME CHF Contract, market went from about 0.98 to peak around 1.23, at $12.5 a tick that’s $31250 per contract, dont know if a limit up trading halt was triggered, but all the same, someone made some money and someone got fried.
Futures are a Zero sum game so for every open position there is a long and a short.
Don’t know what the slippage was like that day in the futures but imagine it wasn’t good, so an equal number of positions would have been smashed; the CME contract is active as well with 30000-50000 open interest most days, doubt anything untoward went on but hope the authorities at least cast an eye over activity leading up to that SNB announcement.