As the stock market continues its seemingly relentless march higher, it’s reasonable to expect that the mood of investors would be positive. However, analysts are getting concerned that optimism is reaching levels seen before at major stock market peaks. According to the Wells Fargo/Gallup Investor and Retirement Optimism Index, the level is at its highest since September of 2000. The latest boost in optimism pushed the index almost 100 points higher over the past 18 months. The 98 point hike in that time frame is the largest increase in the 20-year history of the index (other than during sharp rebounds from sudden plunges).