Share your insights or perspective on the financial matter presented in the input.

Why do stocks tend to trade at high volumes at the end of (or start) the trading day?
Is it possible that mutual funds account for a significant portion of this volume. Investors may decide to buy or sell anytime within a 24 hour period, but the transaction only happened at the close of the market. Therefore at 3:59 pm the mutual fund knows if they will be buying or selling stocks that day.  As nws pointed out the non-market hours are longer and therefore accumulate more news event. Some financial news is specifically given during the time the market is closed. Therefore the reaction to that news has to either be in the morning when the market opens or in the late afternoon if they are trying to anticipate the news.  Also in the US market the early morning trader may be reacting to European market activities.