I have heard from several different sources, e.g. professors, books and traders, that daytraders and quants avoid holding positions overnight and during holidays and weekends. Instead, they sell their positions late in the day and buy it back in the morning. The reason is supposed to be that the trader wants to avoid the exposure to "bad news" during a time he can not act.
But if that is so, someone must be ready to buy those stocks to hold them over night. Who does that? And for what purpose? Are there banks that hold postitions overnight only, as a strategy?