This is not news. Market gains generally have always been dragged along by a small percentage of companies: Focusing on aggregate shareholder outcomes, we find

This is not news. Market gains generally have always been dragged along by a small percentage of companies: Focusing on aggregate shareholder outcomes, we find that the top-performing 2.4% of firms account for all of the $US 75.7 trillion in net global stock market wealth creation from 1990 to December 2020. Outside the US, 1.41% of firms account for the $US 30.7 trillion in net wealth creation. https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3710251 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3710251