S&P 500 concentration grows as $284 billion rotates to emerging markets

The S&P 500 keeps setting records, but the money driving it higher is narrower than the index suggests.

The S&P 500's record run masks a narrowing market: two stocks added $1.42 trillion while active funds sold $284 billion of U.S. equities.

"We have seen other cracks over the past year, and they have not upset the apple cart for very long," said Matt Maley, chief market strategist at Miller Tabak + Co. "It would be foolish to say the AI bubble is about to burst."

Since second-quarter earnings season began July 13, the S&P 500 has added $1.75 trillion in market value, but nearly 80 percent of that gain came from technology — and virtually all of it from Microsoft and Nvidia, according to Bespoke Investment Group. The two companies added a combined $1.42 trillion in market capitalization, while the other 71 stocks in the technology sector lost a combined $22.3 billion. Communication Services shed $299.6 billion, Utilities lost $88.5 billion, and Industrials declined $67.3 billion.

The divergence raises a question for portfolio managers: whether the rotation out of U.S. equities is the start of a longer change in market leadership, or simply another leg of the same AI trade. Emerging-market earnings are expected to grow about 20 percent in 2026, and the MSCI Emerging Markets Index trades at roughly 10.35 times forward earnings versus about 20 times for the S&P 500 — but the index's largest holdings are TSMC, Samsung, and SK hynix, the same AI supply chain driving U.S. mega-cap gains.

Microsoft and Nvidia Added $1.42 Trillion

Microsoft and Nvidia now set the direction of the S&P 500. Tech and AI stocks make up about 40 percent of the index, and the market-cap-weighted structure gives the biggest companies the biggest influence. The S&P 500 can keep hitting new highs even while several major sectors lose hundreds of billions of dollars in value, as the past six weeks have shown.

That concentration creates a false sense of security. An investor looking only at the S&P 500 sees a rising market, which suggests broad participation and improving fundamentals. But the data shows the gains since earnings season began have been extraordinarily concentrated. If Microsoft or Nvidia stumble, their enormous weight can pull the index lower even if hundreds of smaller companies are performing well.

The Rotation's AI Catch

The concentration risk is one reason the shift into emerging markets deserves a closer look. Global long-only funds sold a net $284 billion of U.S. stocks over the 12 months through March 2026 while buying $119 billion in Asia-Pacific excluding Japan and about $71.7 billion in emerging markets. U.S. equity ETFs still attracted $441 billion in the first half of 2026, versus $228 billion for globally diversified ETFs, but non-U.S. ETFs captured 34 percent of equity ETF inflows despite representing only about 20 percent of equity ETF assets. Emerging-market ETFs alone attracted more than $38 billion, a record for the first half of any year.

The valuation gap helps explain the shift. The S&P 500 traded at about 20 times forward earnings as of Aug. 7, versus its 10-year average of 19 times, while the MSCI Emerging Markets Index traded at about 10.35 times forward earnings as of July 31. The MSCI EM Index gained 90 percent cumulatively over the prior three years, versus 76 percent for the S&P 500, as of June 24. A weaker dollar added to the appeal: the WSJ Dollar Index fell 0.8 percent on Aug. 19 to its lowest close since May 13, down about 0.6 percent for the year.

But the emerging-market story is now tied to the same AI cycle. TSMC makes up 15.46 percent of the MSCI Emerging Markets Index, Samsung 7.20 percent, and SK hynix 5.57 percent, as proxied by the iShares MSCI Emerging Index Fund ETF. Taiwan Semiconductor manufactures the advanced chips powering the AI boom, while Samsung and SK Hynix supply the high-bandwidth memory data centers need. Buy emerging markets today, and you're buying a chunk of the same AI supply chain driving U.S. markets to all-time highs.

The question is whether the rotation is real. If gains remain concentrated in Asian technology and semiconductor companies, investors may simply be buying another part of the AI trade. If earnings growth spreads across more countries and industries, the move starts to look like a genuine change in market leadership. The evidence is strong enough to take the rotation seriously, but not strong enough to call it a new era — the difference will come down to whether companies outside the current technology winners can turn today's capital inflows into sustained profit growth.

This article is for informational purposes only and does not constitute investment advice.