Paul Tudor Jones called the 1987 crash. Like, actually called it, made an estimated $100 million when the market lost 22% in a single day, and built a legend off it. Now he's out saying investors could see negative returns over 10 years, and I'd rather you hear it from someone who'll also tell you what to actually do about it. AOL covered the full comments here.

Negative 10-year returns sound apocalyptic, but they're not some freak scenario. It happened after 1929. It happened to anyone who bought Japan at the 1989 peak, and their market took decades to reclaim that high. If you buy at a valuation peak, you can be right about the companies and still lose money for a very long time.

And that's the part of Jones's warning that's grounded in actual math. When stock prices get very expensive relative to earnings, your future returns shrink. That's arithmetic, not fortune-telling. Pay 40 times earnings for something and either earnings grow into the price or you eat a bad decade waiting. I wrote a couple weeks ago about the dot-com warning signal showing up again, and the valuation picture hasn't gotten friendlier since.

Here's my problem with crash prophets though, and I say this as someone who reads all of them. Jones has been right before, spectacularly. But a broken clock that's right once at the exact right moment gets a lifetime of headlines, and timing a crash and timing a decade are different skills. Even Jones isn't telling you to sell everything. The smart version of his warning is: don't build a plan that only works if the next decade looks like 2010 to 2020.

So what do you actually do? Same boring stuff I keep repeating because it keeps being true.

One. Keep buying your index funds anyway. I'm still doing my automatic monthly buys, crash warnings and all, because I don't know when the bad decade starts and neither does anyone else, and missing the good years hurts more than sitting through the bad ones. Dollar-cost averaging is literally built for exactly this environment.

Two. Check your timeline. If you need this money in 3 to 5 years it shouldn't be fully in stocks no matter what the market's doing. That was true before Jones opened his mouth. Your emergency fund, 3 to 6 months of expenses in a high-yield savings account, does double duty as psychological insurance against selling at the bottom.

Three. Lower your expectations, seriously. If you've been modeling 10% annual returns into your retirement spreadsheet, run it again at 4%. Maybe even at 2%. If the plan still works, great, you're built for a lost decade. If it doesn't, better to find out now at 29 or 45 than at 64.

Warren read this story and immediately sent me a text that just said "told you" with no punctuation, which, for him, is gloating. He's been nudging me toward more bonds and fewer crypto positions for months. He's probably a little right. I'm not selling my index funds over a forecast, but I did quietly bump my cash cushion from 4 months to 5. You can respect the warning without obeying the man.

Both things can be true at once, and sitting with that is kind of the whole job. Jones might be right about the decade ahead, and buying every month anyway might still be the best move available to you. The alternative is holding cash and hoping you guess the re-entry point better than a guy who called Black Monday. Good luck with that.