"61-year tenure for average firm in 1958 narrowed to 25 years in 1980—to 18 years now.
A warning to execs: At current churn rate, 75% of the S&P 500 will be replaced by 2027."
"In 2011, a total of 23 companies were removed from the list, either due to declines in market value (for instance, Radio Shack’s stock no longer qualified as of June) or through an acquisition (for instance, National Semiconductor was bought by Texas Instruments in September). On average, an S&P 500 company is now being replaced about once every two weeks. And the churn rate of companies has been accelerating over time."Trechos e imagens retirados daqui.