The phrase "trading day" refers to a day when financial markets are open and active, and trading of stocks, bonds, and other securities takes place. It usually excludes weekends and holidays when the markets are closed. Full definition
With just a handful of trading days left in 2017, global markets are on pace for yet another good year. (fidelity.com)
You will need to take into account unpredictable price fluctuations in the last trading day of crude oil futures, or natural gas futures, for example. (daytrading.com)
No matter how stock prices move, the person will always put $ 50 into the index fund on the first trading day of every month. (businessinsider.com)