Ten companies. That's all it takes to control 40% of the S&P 500 right now. Highest level in over a century.

If you think owning an S&P 500 index fund means you're diversified, think again. You're making a huge bet on Apple, Microsoft, and five other tech giants whether you realize it or not.

Back at the peak of the dotcom madness in 2000, the top 10 stocks only made up 26% of the index. We blew past that. The "Magnificent Seven" (Apple, Microsoft, NVIDIA, Amazon, Alphabet, Meta, Tesla) now sit at about a third of the entire index.

Let's make this personal. Got $100,000 in an S&P 500 fund? Forty thousand of that rides on just 10 companies. Apple has a bad day? Your portfolio has a bad day. NVIDIA reports earnings? Your retirement hangs on how that call goes.

And it gets worse with growth funds. Some of them pack twice the concentration of the regular index. Your "safe" investment? More like a high stakes tech lottery ticket.

We've seen this movie before. After 1980 and 2000, when concentration peaked, those giant companies lagged badly. Between 2000 and 2008, growth stocks got hammered, down 57%. Value stocks? Only fell 9%.

The investors who paid attention to those patterns came out okay. The ones chasing the hot names got crushed.

Why do we keep doing this? Psychology, mostly. Whatever worked recently must keep working, right? These tech companies have been printing money, so naturally everyone assumes that continues forever. Same kind of thinking that has people panic selling at bottoms and loading up at tops. Exactly when you need to keep your head, emotions take over.

Then there's the herd problem. Millions of people own these same seven stocks through index funds. Good news? They all jump together. Bad news? They all tank together. The swings get bigger and bigger.

Real diversification means getting away from these market cap weighted indexes where the biggest names call all the shots. Equal weighted funds give every company the same voice regardless of size. Check out international markets too. They're nowhere near as concentrated as what we've got here.

Or go back to picking individual stocks. Find companies with real competitive advantages, strong balance sheets, prices that make sense. Not because they're trendy. Not because they're huge. Because they're actually good businesses trading at reasonable valuations.

The goal isn't to chase whatever worked last year. It's finding tomorrow's winners while they're still cheap. Takes patience. Takes some work. But that's how wealth actually gets built.

Look, the Magnificent Seven might keep running. Nobody knows. But anyone who's been around markets long enough knows every streak ends eventually. When the market's this lopsided, how you size your positions matters more than which stocks you pick.

Ask yourself this: Should your entire financial future depend on seven companies staying red hot indefinitely?

Because if it does, you're not diversified.

You're concentrated. And that concentration, dressed up as diversification, might be the biggest risk sitting in your portfolio right now.