I'm a little confused about the point about index funds being a small percentage of assets, when there are constantly articles like "Passive investing automatic

I'm a little confused about the point about index funds being a small percentage of assets, when there are constantly articles like "Passive investing automatically tracking indexes now controls nearly half the US stock market." https://www.cnbc.com/2019/03/19/passive-investing-now-controls-nearly-half-the-us-stock-market.html https://www.cnbc.com/2019/03/19/passive-investing-now-contro... His graph shows an arrow pointed at the small sliver on ETFs, but that isn't necessarily the same as passive investing which would include a lot of mutual funds.