Innosight’s third study of company’s ability to maintain leadership positions estimates that by 2018, 50% of the companies on the S&P 500 will drop off, replaced by competitors and new market entrants. Staying at the top of your market-heap is getting harder and harder.
This is often used to show how difficult the business world is now. It’s hard enough to get to the top, and hard to stay there.
Original source: High churn rate in the S&P 500