[asabjorn]

With large early rounds exercising your stock might set you back 50k or more, making you an investor as well as an employee. With the odds of startup success it is advisable to diversify more than that unless you are already wealthy.

[Terr_]

The example that always pops to mind for me is Enron, where many employees owned stock in the company, and the company did a lot of contributions in stock. [0]

So when it imploded, not only did they lose their jobs, but their investments.

[0] http://www.nytimes.com/2001/11/22/business/employees-retirem...