That has huge risks on both ends. On the one end, inflation could destroy CD's. On the other end, 3 and 5 year CD's have reinvestment risk: maybe CD rates will drop to 0-1% for the next 30 years, and your 3% CD's will expire in 3-5 years. If your horizon is less than 30 years and you are OK losing your principal, a TIPS ladder could work. Usually I recommend at least 50% in stocks for the long run though.