這裏的關鍵是加權指數使得標普500嚴重依賴於幾家頭部企業的表現，脫離了股市的真實表現。

問題的關鍵不是有漲必有跌，而是標普500不能正確反映股市的真實趨勢。

The 10 largest stocks in the S&P 500 currently account for about 36% of the index, far higher than at any other time in the last 40 years.