It is often stated that a stock index arbitrage trade is easier to implement when the stock index futures contract price is above its theoretical level than when it is below that value. What...

It is often stated that a stock index arbitrage trade is easier to implement when the stock index futures contract price is above its theoretical level than when it is below that value. What institutional realities might make this statement true? Describe the steps involved in forming the arbitrage transaction in both circumstances. To the extent that the statement is valid, what does it suggest about the ability of the stock index futures market to remain efficient?