Two-Sigma

In statistics, a two-standard-deviation move from the mean, which encompasses approximately 95% of observations in a normal distribution. Traders use two-sigma levels to identify statistically unusual price moves -- Bollinger Bands, for example, default to two standard deviations above and below a moving average. Two Sigma is also the name of a prominent quantitative hedge fund founded in 2001 that manages over $60 billion using data science and machine learning.