Wall Street is going 23 hours. Who takes the keys from a blind algorithm at 2 a.m.?

On Oct. 5, Nasdaq told its market-data customers to prepare for a 23-hour trading day. Three days later, the Securities and Exchange Commission published a Nasdaq rule filing addressing how trading would resume after a market-wide circuit-breaker halt under that expanded schedule. The industry is targeting Dec. 6 for broader overnight trading. Wall Street is rebuilding the machinery for a market that barely sleeps.

There is another machine that needs attention: the automated trading strategy. If its price information turns stale at 2 a.m., who or what takes away its permission to increase somebody else’s risk?