Abstract: After September 11th many government officials have become concerned with the possibility of terrorists launching attacks on the U.S. through the internet. Cybersecurity in industries that form our economys critical infrastructure have been of particular concern. This paper examines the economics of cybersecurity. The economics of externalities, public goods, market failure, and government failure are all explored as they relate to cybersecurity. The financial services industry is clearly an area of critical infrastructure in our economy. This industry provides a case study to examine whether the market is providing the efficient level of cybersecurity or whether government intervention is required.