The most liquid period is the opening. Liquidity starts falling off pretty quickly after the opening. The second most liquid time of day is the close. Trading volume typically forms a U-shaped curve throughout the day. There’s a lot of liquidity right at the opening, it then falls off, reaching a nadir at midday, and then it starts to climb back up, reaching a secondary peak on the close. Generally speaking, this pattern holds in almost every market. It’s actually pretty amazing.
