Is it wrong for cigarette companies and their employees to promote cigarette consumption?

If a person recognizes the serious health risks of smoking cigarettes, is it wrong for him to promote smoking through advertising and other marketing? Does the CEO of a cigarette company have an obligation to his shareholders to maximize the number of people who smoke or the amount that people smoke? Should those shareholders sell their stocks? More generally, do people who work in the tobacco industry face a conflict between their personal profits and the good of others or even society as a whole?