Latest / The Bear Market Podcast with Fexingo: Surviving Downturns, Buying the Dip, and Long-Term Resilience / The Index Diversification Myth in a Top-Heavy Market
Transcript
- Lucas: So the Nasdaq just dropped five percent in five days, the VIX is up thirty-four percent to twenty-one and a half, and yet the Dow is basically flat. If you only own the S&P 500, you might feel like the ground is shaking, but if you own the Dow you're wondering what all the fuss is about. Luna: Right — that divergence is the whole story. The Nasdaq is mega-cap heavy, the Dow is price-weighted and more industrial. But most people's 401k is in something that tracks the S&P 500, which is neither fish nor fowl. Lucas: Exactly. And that brings us to something I've been stewing on for weeks: the index diversification myth. The idea that buying an S&P 500 index fund gives you broad market diversification is becoming less true every quarter. The top ten stocks in the S&P 500 now account for over thirty-five percent of the index's total market cap. Luna: That's wild. I remember when thirty percent was a red flag back in 2021. Has it ever been higher? Lucas: Not since the late 1960s — the Nifty Fifty era, and even then it was maybe thirty-three percent. Today it's driven by the usual suspects: Apple, NVIDIA, Microsoft, Amazon, Meta, Alphabet, Tesla. The top six alone are pushing twenty-five percent. Lucas: Now, if the show has helped you rethink your portfolio allocation or even just saved you from one impulsive trade during this volatile week, that's worth something. If today's episode felt worth a coffee to you, you can find us at buy me a coffee dot com slash fexingo. It's the smallest possible way to keep this thing ad-free and independent. No pressure. Luna: Yeah, honestly a coffee's about what I'd pay for the clarity of not having a commercial break mid-thought. Appreciate anyone who chips in. Lucas: Okay, back to the concentration problem. The Herfindahl-Hirschman Index — that's the standard measure of market concentration — for the S&P 500 has roughly doubled since 2020. It's now above two thousand, which the Department of Justice would call 'moderately concentrated' if it were an industry. Luna: So if I'm a passive investor, I'm not actually buying five hundred companies. I'm buying a heavily tilted bet on six to ten mega-cap tech firms. Lucas: Precisely. And that bet works great when those companies are soaring — like 2023 and early 2024. But it also means your diversification evaporates in a rotation. Look at this week: the Nasdaq down over five percent, the S&P down nearly three, but the Dow is off only four-tenths of a percent. The Russell 2000, small-caps, down two and a half. Luna: So the real pain is concentrated in the same names that drove the gains. That's not diversification — that's leverage on a theme. Lucas: Right. And the options market is pricing that fear. The VIX at twenty-one and a half is elevated, but the VVIX — the volatility of the VIX — is at one hundred and two. That's up eleven percent in a week. That tells me traders are hedging tail risk in the mega-caps specifically, not the broad economy. Luna: Makes sense. The VIX itself is still below the panic levels of March 2020 or even last August's vol spike. But the VVIX is saying 'we're not sure how bad this gets'. Lucas: Exactly. So what do you do if you're an index investor and you want real diversification? One obvious move is an equal-weight S&P 500 ETF. The Invesco S&P 500 Equal Weight ETF, for example, gives you the same dollar exposure to each of the five hundred companies. That immediately cuts your mega-cap exposure from thirty-five percent to two percent. Luna: But historically equal weight has lagged cap weight in strong bull markets because you're underweight the winners. Is now the time to switch? Lucas: That's the timing question nobody can answer. But what you can do is tilt. You don't have to go all-in on equal weight. Maybe you allocate a portion — say twenty to thirty percent of your equity portfolio — to equal weight or to a small-cap value ETF. Small-cap value has a higher historical return over long horizons, and it's uncorrelated enough with mega-cap growth to smooth the ride. Luna: There's also the international piece. The S&P 500 is entirely U.S. companies. If you look at the MSCI All-Country World Index, the U.S. is now over sixty-five percent. So even a global fund is still largely a bet on America. Lucas: And not just America — American mega-cap tech. The MSCI ACWI top ten looks almost identical to the S&P 500 top ten. So if you want genuine geographic diversification, you need to overweight non-U.S. developed markets and emerging markets intentionally. That's an active decision. Luna: It feels like we're saying passive indexing requires active choices now. Lucas: That's exactly what I'm saying. The era of 'just buy VOO and forget it' might be over, or at least it's no longer sufficient. You need to look under the hood. What is your fund actually owning? How concentrated is it? Because the index itself doesn't care about your diversification — it just weights by market cap. Luna: And market cap weighting means the more a stock goes up, the more you buy. That's a momentum strategy, not a value or diversification strategy. Lucas: Right. So the takeaway isn't 'sell everything and go to cash.' It's: take a look at your portfolio's effective concentration. If the top ten stocks in your index fund are more than thirty percent of your equity allocation, you might want to consider an equal-weight or multi-factor ETF to balance it out. Even a ten percent shift could reduce your correlation to a single sector drawdown. Luna: And now, with the VIX at twenty-one and the VVIX elevated, it's a good time to check before the next leg down — not after. Lucas: Exactly. We'll keep watching the spread between the VIX and VVIX. If the VVIX stays high while the VIX drifts lower, that's a sign the market is complacent about the broad economy but still scared of a few names. That's the kind of signal that should make you question how diversified you really are.