How many seconds is the US stock market open per year?

Question

Regular US equity trading hours are 9:30 to 16:00, roughly 252 trading days a year. Solve in your head. About how many seconds of regular trading are there in a year? Aim: under 30 seconds.

Accepted Answer

Chain the clean factors: - Session length: 6.5 hours = 6.5 	imes 3600 = 23{,}400 seconds per day. (Route: 6 	imes 3600 = 21{,}600, plus half of 3600 is 1800: 23{,}400.) - Per year: 23{,}400 	imes 252. Route: 23{,}400 	imes 250 = 5{,}850{,}000 (that's 23{,}400 	imes 1000 / 4), plus 23{,}400 	imes 2 = 46{,}800: 23{,}400 	imes 252 = 5{,}896{,}800 \approx 5.9 	imes 10^6 	ext{ seconds.} Call it about 6 million seconds of regular trading per year. Takeaway. Good Fermi answers pick factors that divide nicely: 	imes 252 = 	imes 1000 / 4 + 	imes 2 is one clean move. The number itself is us…

How many seconds is the US stock market open per year?

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