The CBOE's Volatility Index is known by ticker symbol VIX. It is a measure of the level of implied volatility and was developed by the CBOE in 1993. VIX measures the volatility of the U.S. stock market and is updated throughout the day by the CBOE in real-time using OEX bid/ask quotes. VIX is calculated by taking the weighted average of the implied volatility of eight OEX calls and puts with an average time to maturity of 30 days. VIX is therefore a measurement of 30 day index options. It is not a measure of the volatility of any one individual stock or option. And it does not measure the implied volatility of any other index other than the OEX. However, many traders use it as a general indication of index option implied volatility.