Armchair investors have been selling stock. So have pension funds and mutual funds, as well as a whole other category of investors — nonprofit groups, endowments, private equity firms and personal trusts.
The stock market is off to its best start since 1987, but these investors are expected to dump hundreds of billions of dollars of shares this year. So who is pushing prices higher? In part, the companies themselves.
https://www.nytimes.com/2019/02/25/business/stock-market-buybacks.html