The US stock market’s ageing IPO decline is drawing attention, as analysts warn that fewer new companies are entering public markets.
According to economist Owen Lamont, the U.S. equity market is becoming older by several measures, reflecting a slowdown in initial public offerings (IPOs).
Just as populations age, stock markets age when there are fewer new entrants. In financial terms, this means fewer IPOs the process through which companies go public and join the market.
Since 2000, IPO activity in the United States has steadily declined, leading to older average company ages both at founding and listing.
Large, established firms now dominate the market. For instance, Microsoft, founded in 1975 and listed in 1986, represents the broader trend of older companies carrying significant market weight. Another key measure is “new issue weight,” which tracks the share of the market made up of companies listed within the past three years.
When this figure rises, it signals a younger, more dynamic market driven by new entrants or strong performance from recent listings. As of November 2025, the new issue weight stood at just 1.3%, well below the historical average of 4.6%.
This sharp drop reflects what Lamont describes as an “epic new issue drought,” with relatively few companies going public and those that do often having lower valuations. The rise of private markets may partly explain the trend. Companies are increasingly staying private for longer, reducing the flow of new listings into public markets. The ageing market raises questions about long-term growth and innovation.
Read: Elon Musk Suggests SpaceX Could Go Public in 2026 IPO
However, analysts note that while fewer IPOs can limit fresh opportunities, they do not necessarily signal an immediate decline; they do highlight a shift in how companies raise capital.
