Prices are near historical peaks, and the ratio still says the market is cheap relative to its growth. I'd be suspicious of that rather than comfortable.
What happened
The S&P 500 forward PEG ratio just hit 0.70, the lowest in 30 years. PEG is the price-to-earnings ratio divided by expected earnings growth.
Why it fell
It didn't fall because prices fell. It fell because the denominator got bigger, and that denominator is analyst forecasts, not reported earnings. If earnings miss even slightly, estimates get cut and PEG jumps right away.
The concentration problem
The low reading likely leans on very large growth estimates for a handful of mega-cap AI and tech names. I haven't seen the PEG with those names removed, so I won't claim what it looks like.
A low PEG isn't a safety signal
A CFA Institute analysis published on 25 February 2025 looked at S&P 500 PEG data from 1985 to 2020 and found that a PEG below 1.0 was rare and unreliable as a stand-alone market-timing signal. And the trailing measures point the other way:
- Buffett Indicator (total market capitalisation / GNP): 238.6% as of 7 October 2026.
- Shiller CAPE (Multpl): 41.07 as of 1 October 2026.
The same problem I look at in derivatives
What's priced in for the future versus what actually gets realised. A forward number is only as good as the forecast behind it, which is the same reason I track positioning rather than trusting a single indicator in Crypto Derivatives Intelligence.
My read
Owning the index today is less a bet on the broad corporate economy and more a bet that a few companies execute close to perfectly on AI monetisation. They might. I just think that's the bet to name.
What would change my mind
Earnings coming in at or above estimates, and forward estimates holding for the rest of the index, not just the mega-caps. If both happen, the low PEG is closer to earned than I'm giving it credit for.
Sources: CFA Institute (25 February 2025); Buffett Indicator data as of 7 October 2026; Multpl Shiller CAPE as of 1 October 2026. First shared on LinkedIn.
This article is for education only and is not financial advice. Markets are volatile; do your own research and manage your risk.
