The Cap Weighted Index Is the Most Efficient

There are times when the market is mostly efficient but during those boom bus periods that's that's where things get a little crazy so back to the 2000 year as you discussed when the s&p 500 is trading at 30 or 40 times and the tech sector at 100 and NASDAQ at 600. If you're a cap weight you can't sell those you got to hold them within the index meaning the index portfolio construction is going to be wildly over weighted on wilder most overpriced stocks exactly by definition.