On the worst day for American shares since March 2003, sell orders were so heavy that at one point the New York Stock Exchange could not process them all.
So far this year, more than 95 have started trading on American markets alone, many of these on the New York Stock Exchange, which sees ETF listings as a key source of listings income.
On the flip side, the Nasdaq/ICE deal would effectively split the NYSE into two parts, with ICE taking the NYSE's US derivatives unit and the Nasdaq taking its equity unit and listings business.