There are four types of arbitrage: 1. Cross-cycle arbitrage: for example, futures cross-cycle arbitrage can use short-term and long-term contracts for arbitrage. 2. Cross-species arbitrage: For example, gold and silver can use positive correlation to arbitrage, or they can use negative correlation between gold and silver and the US dollar to arbitrage. 3. Cross-market arbitrage: Different markets can also carry out arbitrage, such as futures, spot and physical objects, which can all arbitrage each other. 4. Cross-regional arbitrage: China conducts the same kind of arbitrage transactions with the United States, Hongkong, Europe, Japan and other different trading places.