CBOE's volatility indexes are key measures of market expectations of near-term volatility conveyed by option prices. The indexes measure the market's expectation of volatility implicit in the prices of near-term or mid-term options. The indexes are quoted in percentage points, just like the standard deviation of a rate of return, e.g. 19.36. CBOE disseminates the index values continuously during trading hours. The indexes are leading barometers of investor sentiment and market volatility relating to listed options.