*This all makes sense to me for a publicly traded company, where the value of each share can be easily determined, but how does it work for a private company? *
I used to work for a subsidiary of SAIC which at the time was a very large privately held, employee owned company. They periodically (quarterly or annually) valued the stock using some accounting black magic. Because the stock is not publicly traded, you couldn’t just go to your broker and sell it. But I never owned any so I don’t know the procedure for selling it.
Also, do people usually just immediately sell the shares that they buy with the option, thus pocketing the difference?
Depends on the person, and the option plan. Some companies require you to hold the stock for a minimum period before selling it, but I think it is more common to allow you to do whatever you want once your options vest (you didn’t ask about vesting, but there is usually a waiting period from the time the option is *granted *to you, which is when your option number of shares and price is set, until it is *vested *and you can actually exercise it). Many companies want employees to hold stock to give them a continued interest in seeing the company do well.
Are there any penalties for doing that (in terms of tax or anything else)? Or do people usually hang on to the shares for a little longer?
This depends on the type of option, whether it is an incentive option, or a non-qualified option (you need to ask which one it is). I am rusty on the difference. In some cases, exercising the option is a taxable event and you must declare as income the difference between the price you paid and the market value. In this situation many companies allow you to exercise a “sell to cover” (sometimes called a cashless exercise) where you exercise the options then sell enough stock to pay for the shares plus resulting taxes. In other cases you need not declare the income until you realize it by selling the stock.
In addition, there’s also a chance that the company may be bought out by another private company in the near future. How is this going to change things? I have a feeling that it might be a good idea to exercise the option so that I hold shares of the company when it is being bought. Is that correct? What are the risks? What is going to happen if the deal doesn’t pan out?
This is very dependent on the individual situation and nobody can give you generic advice on this. Generally acquisitions occur at somewhat above market value but it’s not always the case. Holding the stock carries the same risk as holding any other stock of any other company: It might go up, and it might go down.