The long position which is taken by the holder (buyer) of an option. In other words, the long side has the right to exercise it, either to buy the underlying asset (if a call) or to sell it (if a put), to close the position with an offsetting trade, or let it expire worthless on expiration date. Long call options (bullish position) have a positive delta, whilst the delta of long put options (bearish position) is negative. Generally, a long option position has a positive vega. For example, if an investor is long an option and volatility rises, the position increase in value even if underlying price remains static.