Just noticed something worth thinking about. The markets have been absolutely crushing it under Trump -- the Dow up 57%, S&P 500 up 70%, Nasdaq up 142% during his first term. And we're seeing it again now, with all three indexes near all-time highs in 2025. Pretty wild performance.

But here's what caught my attention: the real story isn't just about Trump's policies. AI hype, rate cuts from the Fed, corporate tax cuts boosting buybacks -- yeah, all of that's playing a role. S&P 500 companies are projected to hit over $1 trillion in buybacks for 2025. That definitely props things up.

The thing is, there's this one metric that's been screaming a warning for months. The Shiller P/E ratio -- it's basically the 10-year inflation-adjusted price-to-earnings measure. Since 1871, it's averaged around 17. Right now? It's sitting at 40. That's the second-highest valuation level in 155 years. Only the dot-com bubble was worse.

And here's the kicker: every single time this ratio has exceeded 30 in the past 155 years, it's been followed by significant declines. Every. Single. Time. We're talking about a track record that goes back more than a century.

I get it -- the bull market feels unstoppable right now. Valuations seem justified by AI growth potential, quantum computing opportunities, all the narratives. But valuation premiums like this just don't stick around forever. History is pretty clear on that.

The Shiller P/E isn't a timing tool, so nobody can say exactly when the correction hits. But it's never been wrong about the eventual outcome. If we're looking at historical precedent, this bull market is running on borrowed time.

Worth keeping an eye on if you're holding equities or thinking about adding. The data doesn't lie.