BobbyCaps : Idk I just opened an account after realizing you can’t do a lot on Robinhood in terms of functionality.

BobbyCaps : From MooMoo help center.
US stocks Pre/Post Market time and trading rules
US stocks Pre-Market and Post Market data update period:
1)Pre-Market(ET): 4:00~9:30
2)Post Market(ET): 16:00~20:00
The latest market data sort the Pre/Post Mkt. When it is not in the market data update period, the market data of the latest moment of the history will be sorted. The specific rules are as follows:
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PS: T indicates a trading day, then T-1 is the previous trading day. For non-trading days, the latest data for the most recent trading day will prevail.