Market Holiday
A day when a stock exchange is closed and no regular trading happens. US markets (NYSE/Nasdaq) and Korea's KRX each follow their own calendar.
A market holiday is a day the exchange stays shut and no regular trading takes place. New Year's Day and Christmas are the obvious ones, but because US markets (NYSE and Nasdaq) and Korea's KRX and KOSDAQ run separate calendars, one side is often open while the other rests. When Korea closes for the Lunar New Year, for instance, US markets carry on as usual.
On top of full closures, US markets have early-close days, when trading wraps up in the early afternoon instead of at the normal bell. The Friday after Thanksgiving and Christmas Eve are the usual ones, ending a few hours ahead of schedule. If you don't know these dates, it's easy to get confused about when the day's closing price is actually set.
Crypto is the one exception. Coin markets like Bitcoin trade 24 hours a day, every day of the year, with no weekends or holidays, so the idea of a market holiday simply doesn't apply. Stocks and ETFs are different: when the exchange is closed, no new closing price is printed for that day at all.
For anyone making predictions, holidays matter more than they look. A call you placed expecting it to settle on a certain day's close can slip a day or two when that day turns out to be a holiday. LDBD anchors to the XNYS (US) and XKRX (Korea) exchange calendars and keeps an overrides table for one-off closures, so these dates get handled automatically. There's also a free tool to check whether a market is open right now and when the next holiday falls.
How LDBD uses it
LDBD derives every prediction's start price and resolve date straight from the exchange calendar. A call submitted while the market is closed locks in the last close as its start price (the dormant window), and if its resolve date lands on a holiday it rolls forward to the next trading session's close. Combining the XNYS and XKRX calendars with an overrides table for temporary closures keeps the trading days accurate, so nothing is ever scored against a day the market never actually traded.
FAQ
Do US and Korean markets share the same holidays?
No. National holidays differ: the US closes for Independence Day and Thanksgiving, while Korea closes for the Lunar New Year (Seollal) and Chuseok. The main shared closures are New Year's Day (Jan 1) and Christmas (Dec 25); most other holidays don't line up. If you follow both US and Korean stocks, you have to track two calendars separately.
What happens to a prediction I place on a holiday or early-close day?
On LDBD, a call submitted while the market is closed takes the last close as its start price, and if its resolve date is a holiday it shifts to the next open session before being scored. That way no bet is ever settled against a day the market didn't trade.