Only 52 US companies are in Fortune 500 list since 1955(aei.org)
aei.org
Only 52 US companies are in Fortune 500 list since 1955
https://www.aei.org/carpe-diem/only-52-us-companies-have-been-on-the-fortune-500-since-1955-thanks-to-the-creative-destruction-that-fuels-economic-prosperity-2/
The AEI is making the point there is more creative destruction than people think - which is fair.
But Mobil is counted as if it isn't in the top 500 companies now because it merged. But it wasn't just gobbled up - if it was independent it would clearly be top 500 still. If you were a shareholder in 1955 you'd be pleased.