Nasdaq Launches Overnight Session in December as Wall Street Moves Toward Nearly 24-Hour Trading

Wall Street is moving toward nearly 24-hour trading. Nasdaq is launching an overnight session in December, and an all-night exchange is next.
According to SEC data, foreign accounts are the single largest slice of volume in the overnight window, from 8 p.m. to 4 a.m., with dealers and prop traders filling much of the rest. Long-only institutions almost sit it out until regular hours open.
The author warned that the overnight session is the thinnest, least institutional part of the day, which means less liquidity, wider spreads, and prices that can gap on small orders.