My colleague Conor Sen recently made a bold prediction: Government will be the driver of the U.S. economy in coming decades. The era of Silicon Valley will end, supplanted by the imperatives of fighting climate change and competing with China.

This would be a momentous change. The biggest tech companies — Amazon.com, Apple Inc., Facebook Inc., Google (Alphabet Inc.) and (a bit surprisingly) Microsoft Corp. — have increasingly dominated both the headlines and the U.S. stock market: