The spread between bulls (55.2%) and bears (15.6%) in the Investors Intelligence Poll moved up to 39.6% this week, the second-highest level since the low in March 2009. The last time the spread was this high was back in April of 2011, which coincided with a top in the S&P 500 and subsequent decline of over 20%.
Before that, you have to go back to the October 2007 peak to find sentiment at a similar extreme.