Assuming a premium of 6, the cost of the option would be $600. This purchase leaves you with $5,400 to invest in T-bills for six months. Assuming an interest rate of 10% and that the T-bill is held until maturity, the $5,400 would earn interest of $270 over the six month period. The interest earned would effectively reduce the cost of the option to $330 ($600 premium minus $270 interest). If the price of XYZ rises by more than $ per share, your long call will realize the dollar appreciation at expiration of a long position in 100 shares of XYZ stock but with less capital invested.
