Hello as I know price volatility is another major issue affecting trading after hours. Stocks with limited trading activity tend to show significant price swings than you would expect during normal trading hours. New stories that develop outside business hours will greatly impact prices during off-hours trading sessions. I can also say that the low trading activity associated with trading after hours leads to an increase in the quotes spread between the bid and offer prices. In addition to affecting the share price, you may find it difficult to fulfill your orders. In the article you can find more information about what is after hours trading