You can place market or limit orders during regular stock market hours are Monday-Friday 9:30 a.m. to 4 p.m. ET.
SoFi also offers Extended Hours Trading. You are able to place limit orders during after-market and pre-market hours. SoFi supports extended hours trading for 30 minutes before market open (9:00 am - 9:30 am Eastern) and 4 hours after market close (4:00 pm - 8:00 pm Eastern).
Market orders placed outside of regular market hours will be Market on Open orders and will execute when the market opens.
To learn more about order types available with SoFi, please visit our Help Center Article: What are the different order types for Active Investing?