The mode, in statistics, is the value that appears most often in a set of data. For a continuous quantity, where exact repeats are rare, it is the point at which the probability distribution peaks, seen as the tallest bar of a histogram. It is one of three common measures of the centre of a distribution, with the mean and the median. A data set can have more than one mode, in which case it is called bimodal or multimodal.
In a symmetric distribution the three measures coincide. In a lopsided one they separate, which is informative: under the lognormal distribution used for share prices, the mode lies below the median, which lies below the mean. In market data, the most common trade size in many shares is a single round lot, and the price at which the most volume has traded in a session is treated by some traders as a reference level.