An index option which gives the holder the right, but not the obligation, to buy upon exercise the value of an underlying index at a stated strike price before or at expiration.

Buying an index call is a bullish strategy as it represents a bet on a rise in the level of the underlying index. The value of the call tends to rise as the level of the underlying index goes up, and this gain will automatically factor in to a rise in the value of that index when its level crosses the option’s strike upwardly.