it is certainly possible. When the market begins to take a significant tumble, it can pull down the price of all stocks, even ones that are not involved in the “sub-prime” crisis. It's called systematic risk. Chapter 16 of my free book at http://www.invest-for-retirement.com addresses this issue.BTW, it is not recommended to hold company stock in your 401(k). You have pinned too much hope in the performance of one stock. Retirement accounts should be funded with mutual funds or some other form of diversified investment.