Just 60 of the Fortune 500 of 1955 remain in the hallowed group. The rest (like American Motors, above, subsumed by Chrysler in 1987) have been largely the victims of changing times, tough competition or their own missteps.
What's happening: Tom Siebel, founder of C3.ai, an artificial intelligence firm that serves big corporations and the Army, says that this is an existential moment for current Fortune 500 companies that don't move quickly to adapt to the new age of AI and robotics.