His “fat-finger” trade sent stocks tumbling on Sunday, with Nordic markets hardest hit.
The Stockholm OMX 30 index fell 8% in 5 minutes at the start of trading, before recovering most of its losses.
The Danish, Norwegian, German, Italian and French markets were also affected and trading was briefly halted.
The Bank of New York said in a statement: “One of our traders made an error when entering a transaction. Within minutes, we identified the error and fixed it.”
Sweden’s financial watchdog said it was investigating the drop and had contacted the US stock market Nasdaq, which operates the Stockholm stock exchange.