I do not care who you work for, do not be over invest in that company's stock. If they have an ESPP (employee stock purchase plan) where you can buy stock at a discount, do it, but then seel the stock when you can if the overall amount in your ESPP is out of balance with the rest of your investments. Additionally, do not own large amounts of company stock in your 401(k).
The reason for the above is diversity. You are already relying on your job and your company 100% for your income, do not rely on your company's performance for your retirement.