The chart below is the Investors Intelligence sentiment index. As you can see, the bull to bear reading as of Tuesday was at the highest point since 1987. This run from being at almost the most bearish ever to being near the most bullish ever is the most remarkable run in the history of this survey. Generally, it doesn't make sense to buy at the top, but keep in mind this is a near term indicator. To me, it means a correction could be coming. However, falling 5%-10% doesn't mean a bear market will arrive as the economy and earnings look like they will be strong this year.
While the Investors Intelligence survey is very optimistic, the NDR sentiment poll makes it look like investors are even more euphoric. As you can see from the chart at the bottom, the NDR is at 78.9% which is a new record. It indicates that when investors are optimistic, it's bearish and when they are pessimistic, it is bullish. The indicator goes back to 1995 and was last updated on Tuesday. When the index is above 66, it means stocks lose 2.89% in the next year and they rally 24.47% of the time. Based on the breakdown, you'd assume the higher it gets, the lower the returns and the lower the chances of a positive return. This looks like the chart showing how low unemployment equals bad returns. Almost every indicator I see says long term returns are going to be low.