Traders can't get enough of options betting on more gains in the S&P 500 Index, a gauge that has for months been in the shadow of its more volatile rival, the Nasdaq 100. The surge in bullish positioning signals growing confidence that the market rally is broadening beyond the technology-heavy benchmark.

More than 4 million call contracts on the benchmark equities index changed hands on Tuesday, a record, while the volume of puts remained in line with the average. The lopsided activity underscores a shift in sentiment as investors increasingly wager on sustained upside across the broader market.

Simplex Trading's Jason Coogan, who trades in the S&P 500 options pit at the Cboe Global Markets, described the setup in the two days through Tuesday as a "one-way flow in orders." The unprecedented call volume reflects a consensus that the index has room to run after months of consolidation.

The options frenzy coincides with the S&P 500's steady climb, suggesting institutional and retail participants alike are positioning for further gains. With put volumes muted, the market structure appears skewed to the upside, reinforcing the bullish narrative.