In exchange-based trading, the term Asian session refers to the trading period defined by the trading hours of Asian and Oceanian exchanges. This session runs from around 11:00 PM GMT until 8:00 AM GMT.
The Asian session, European session and North American session together make up a full trading day. The Asian session is the first session in a trading day. It is followed by the European session which opens 8 hours later at around 7:00 AM GMT. The Asian session overlaps the European session by 1 hour (7:00 AM GMT until 8:00 AM GMT). The North American session is the last trading session in a trading day, and does not overlap the Asian session.
In forex trading, the Asian session is often referred to as the Tokyo session due to the dominance of Tokyo exchanges in Asian and Oceanian forex trading activity.
Interactive stock broker comparison