Order Imbalance and the Pricing of Index Futures

This study examines whether the direction and magnitude of the aggregate order-imbalance of the index stocks can explain the arbitrage spread between index futures and the underlying cash index. The data are for the Asian financial crisis period and hence entail wide variations in order imbalance and the index-futures basis. The analysis controls for realistic trading costs and actual dividend payments. The results indicate that the arbitrage spread is positively related to the aggregate order imbalance in the underlying index stocks; negative order-imbalance has a stronger impact than positive order imbalance. Violations of the upper no-arbitrage bound are related to positive order imbalance and violations of the lower no-arbitrage bound are related to negative order imbalance. Asymmetric response times to negative and positive spreads can be attributed to the difficulty, cost, and risk of short stock arbitrage when the futures is below its no-arbitrage value. The significant relationship between order imbalance and arbitrage spread confirm that index arbitrageurs are important providers of liquidity in the futures market when the stock market is in disequilibrium. Hong Kong Institute for Monetary Research