Gorilla Index

In the late 1990s, fewer and fewer stocks were responsible for the majority of the gains in the stock market. To capture this phenomenon, we created the Gorilla Index, a group of only 17 stocks that accounted for over 25% of the market-capitalization of the S&P 500. We warned that a breakdown in this group of stocks would be a red flag that a bear market may have begun. This index broke through key support levels in May 2000, just two months after the market peak.

Today, a similar dynamic has developed, except for even fewer stocks account for an even greater share of the S&P 500’s market-capitalization. And as was the case in the Tech Bubble, where these stocks go, the rest of the market will undoubtedly follow…

Gorilla Index S&P 500 The Gorilla Index is comprised of <2% of stocks in the S&P 500 Index but accounts for >33% of the S&P 500's market capitalization. Updated: Oct 03, 2025 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 2017 2018 2019 2020 2021 2022 2023 2024 2025 InvesTech Gorilla Index vs. S&P 500 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 17 18 19 20 21 22 23 24 25 InvesTech Gorilla Index vs. S&P 500 2016