This will be an assumption you have. Are there facts to prove this? I have not seen big dumps happening on weekends repeatedly. It can happen in a while just like it also happens on Monday to Friday. It is coincidence. I do not trade much these days but I know of traders who trade weekends mostly and they make great gains doing that. Maybe trading at the weekend is the only time and opportunity they have away from work. The important thing is to know when to make trades and not to limit it to week days. Trade any day you want.