Massive IPOs are emerging one after another, marking the end of the era of "scarcity of supply" in the U.S. stock market.

In the past twenty years, the U.S. stock market has mostly been in a "supply scarcity" state. The amount of stocks held by the public has been decreasing year after year, with companies in the S&P 500 index alone buying back nearly $12 trillion worth of stocks. Now, investors will soon realize what it means when the supply suddenly reappears. According to JPMorgan's forecast, even after deducting buybacks, initial public offerings, secondary offerings, and other stock sales transactions will add about $1.5 trillion worth of stocks to the U.S. stock market. If this turns out to be true, it will usher in the strongest period of stock issuance since the late 1990s.