'Magnificent 7' stocks have lost $2 trillion so far this month, driving the S&P 500 decline: Chart of the Day

The S&P 500's ( ^GSPC ) decline in June looks like a market sell-off. Under the hood, it is mostly a megacap problem.

The "Magnificent Seven" — Microsoft ( MSFT ), Amazon ( AMZN ), Apple ( AAPL ), Alphabet ( GOOG , GOOGL ), Nvidia ( NVDA ), Tesla ( TSLA ), and Meta ( META ) — have erased roughly $2 trillion in market value this month, according to Yahoo Finance analysis.

That accounts for more than two-thirds of the S&P 500's total market-cap loss in June.

The group's biggest drag has come from Microsoft and Amazon, which have each lost more than $350 billion in market value this month. Apple and Alphabet have each shed roughly $300 billion, while Nvidia and Tesla have lost about $260 billion and $200 billion, respectively.

The result is a top-heavy index doing what top-heavy indexes do: moving with its largest stocks.

It's not that the rest of the market is very strong so much as the weakness is concentrated.

The Magnificent Seven are down a median 9.7% in June, while the rest of the S&P 500 has a median gain of 0.3%. That split helps explain why the index feels heavy even though many stocks are still holding up.

The same pressure showed up in Tuesday's sell-off , when AI and chip-linked winners absorbed the biggest damage while the broader tape looked less broken underneath.