In June 2007 the Chicago Board Options Exchange (CBOE) announced that it is beginning to publish daily data on the value of the CBOE S&P 500 PutWrite Index (ticker symbol PUT). PUT is an award-winning benchmark index that measures the performance of a hypothetical portfolio that sells S&P 500 Index (SPX) put options against collateralized cash reserves held in a money market account. The daily historical data for the PUT Index now extends back to June 30, 1986.
The PUT strategy is designed to sell a sequence of one-month, at-the-money, S&P 500 Index puts and invest cash at one- and three-month Treasury Bill rates. The number of puts sold varies from month to month, but is limited so that the amount held in Treasury Bills can finance the maximum possible loss from final settlement of the SPX puts.