NEW YORK (Reuters) - Strong earnings boosted U.S. stocks on Tuesday, driving the S&P 500 .SPX to a record high while also sending a popular options-based gauge of expected price volatility down to a more than 23-year low.

Traders work on the floor of the New York Stock Exchange (NYSE) in New York, U.S., July 20, 2017. REUTERS/Brendan McDermid

The CBOE Volatility Index .VIX, better known as the VIX and the most widely followed barometer of expected near-term stock market volatility, was down 0.24 points to 9.19, after earlier falling to 9.04, its lowest since December 1993.

A close at its current level would be its lowest ever.

The VIX is derived from the price of S&P 500 Index .SPX options. A low VIX reading typically indicates a bullish outlook for stocks.

The volatility index, whose long-term average level is around 20, has been extremely subdued this year as a surging stock market has chilled demand for options that provide protection against price declines, driving down the index itself.

On Monday the index closed below 10 for the eighth straight day, marking its longest such streak ever.

Market experts peg the relative tranquility in stock market gyrations to a mix of factors including a generally upbeat macroeconomic backdrop and the lack of any big, risky events that could potentially stoke volatility.

And the sense of calm is not restricted to the equity markets. Bank of America Merrill Lynch's gauge of one-month Treasury market volatility .MERMOVE1M was at 46.9963, a record low.

To be sure, some traders in the options market have taken advantage of subdued levels of volatility to load up on contracts that profit from a pick-up in stock gyrations.

“Over the past few days, we’ve seen a tremendous amount of options activity in VIX,” Pravit Chintawongvanich, head of derivatives strategy at Macro Risk Advisors in New York, said in a research note to clients.

“These trades all have a common theme – investors expect volatility to move higher after the summer,” he said.

On Friday, more than a million VIX options contracts traded in one go. The trader makes money as long as the VIX is between 12 and 35 at the October expiry.