Why does $QQQ / $NDX outperform?

Only the top 7 companies make up 50% of the index: $AAPL, $MSFT, $AMZN, $GOOG / $GOOGL, $FB, $INTC, $NVDA

The top 5 alone (AAPL, MSFT, AMZN, GOOG/GOOGL, FB) make up 45% of the index.

The top 4 alone (AAPL, MSFT, AMZN, GOOG/GOOGL), make up 40%. https://t.co/M7PbbzmZNH