Are stocks expensive? This 30-year-low stat says otherwise.

Big names in tech such as Nvidia ( NVDA ) and AMD ( AMD ) may have just ripped to record highs, but that doesn't mean the overall stock market is overheated.

In fact, investors could make the argument that stocks look downright cheap.

One piece of evidence for that is the price-to-earnings growth ratio, better known as the PEG ratio. It measures a stock's valuation relative to its expected earnings growth, with a lower PEG ratio generally suggesting a more attractive valuation.

The S&P 500's PEG ratio just hit a 30-year low, according to data from Yardeni Research (see chart below).

With the outlook for corporate earnings remaining robust, it almost makes no sense to see such a low PEG ratio.

As of today, the S&P 500 is expected to report year-over-year earnings growth of 29.5% for the recently completed third quarter.

If 29.5% is the actual growth rate for the quarter, it will mark the third consecutive quarter of earnings growth above 25%, according to FactSet. It would also represent the eighth straight quarter of double-digit percentage earnings growth.

For the fourth quarter, Wall Street analysts are calling for earnings growth of 27.6%.

Analysts are predicting year-over-year earnings growth of 32.4% for 2026 when all is said and done.

"The bull market continues to deserve the benefit of the doubt. Beneath the surface, a healthy reset in prices and valuations is creating opportunities as the fourth quarter begins," Truist chief strategist Keith Lerner said, adding, "Still, the weight of the evidence currently supports remaining overweight equities, maintaining our preference for U.S. growth, and selectively adding income opportunities."

Brian Sozzi is Yahoo Finance's Executive Editor, host of the Sozzi Unleashed morning show, the ' Power Players With Brian Sozzi' podcast and a member of Yahoo Finance's editorial leadership team. Follow Sozzi on X @BrianSozzi , Instagram , and LinkedIn . Tips on stories? Email brian.sozzi@yahoofinance.com.