Markets are priced by people, and people swing between two emotions: the fear of losing money and the greed to make more of it. The CNN Fear & Greed Index is an attempt to compress that emotional state into a single number between 0 and 100 — 0 being maximum fear, 100 being maximum greed, 50 being neutral. It is one of the most-watched sentiment gauges in retail and professional finance, and one of the most misunderstood.