Market sentiment and contrary opinion as measured by various indicators have been used by traders for many years. The theory of contrary opinion asserts that if a majority of traders agrees on the direction of a market move, then the odds are significant that prices will, in fact, move in the opposite direction. Various measures of market sentiment have been used over the years in attempts to apply contrary opinion effectively in the markets. Among these are odd lot short sales, options volatility, broker opinion surveys, and trader opinion surveys. The good news is that the theory of contrary opinion is correct; the bad news is that the traditional measures of contrary opinion either tend to be LATE or generally unreliable.