Oct. 16 (Bloomberg) -- The benchmark index for U.S. stock options reached 80 for the first time in its 18-year history, driven higher by equities extending the biggest slide since 1987 on concern the economy will continue deteriorating.

The VIX, as the Chicago Board Options Exchange Volatility Index is known, increased 17 percent to 81.13 at 11:14 a.m. in New York after earlier rising to 81.17. The index measures the cost of using options as insurance against declines in the Standard & Poor's 500 Index, which lost 4.5 percent. The S&P 500 tumbled 9 percent yesterday. Today's VIX record eclipsed the peak of 76.94 on Oct. 10, when U.S. stocks completed their worst week since the 1930s.

``It's absolutely uncharted territory,'' Matt Shapiro, a VIX options trader at Stutland Equities LLC, said in an interview from the CBOE floor. ``It's very frightening and there's a huge explosion to buy any options on the VIX, especially 70 and 90.''

The VXO Volatility Index, a predecessor to the VIX that reflects the price of options on the S&P 100, climbed 23 percent to 84.30. It jumped to 103.41 on Oct. 10. The ``old VIX'' set an intraday record of 172.79 a day after the October 1987 stock- market crash.

To contact the reporter on this story: Jeff Kearns in New York at jkearns3@bloomberg.net.

Last Updated: October 16, 2008 11:16 EDT