It's notable that the turnover of listings on major stock indexes has generally increased over time. Everyone knows that companies have lifecycles, and part of

It's notable that the turnover of listings on major stock indexes has generally increased over time. Everyone knows that companies have lifecycles, and part of the old 20th century career path was that the lifecycle was sufficiently large that you could stay at a big employer forever. But nowadays, that's quite uncertain. In effect, you can assume that software you write for a company's business process is "already on life support", moments after it enters production. Whatever angle they had to get sales, it is not sustaining, and the next market cycle will cause a crisis in which they are acquired by an unrelated business. The software tribes tend to have a kind of family tree as they jump ship from one business to the next; e.g. you can do an analysis of game development practices by looking at Mobygames credit lists and old articles in GDMag, and observing who goes where, and when a certain pioneering technique starts to diffuse from one team out into the industry.