For most of the 20th century the companies that brought in the most money also employed the most people. For example, in 1962 General Motors was one of the top five companies by market capitalization and employed more than half a million workers. In fact, four out of the five most highly capitalized companies that year employed more than 100,000 people each. The fifth, IBM, had over 80,000. But the 21st century has seen a reversal of that pattern. By 2012, only one of the five largest companies by market capitalization (Walmart) employed more than 100,000 people, and it had way more—2.2 million. The other four—Apple, Google, Exxon, and Microsoft—had a combined total of just 300,000.

It seems that we have entered the age of the employee-less company, led by the high-growth, highly profitable tech industry. And while that might be great for investors, it’s less great for the middle class. After years of high unemployment and persistent underemployment, job creation—especially of full-time, adequate-wage jobs—is critical.

A new paper from the Brookings Institution digs into this phenomenon of highly productive, low-employment tech firms. Part of it is due to the nature of digital work, which involves fewer full-time employees compared with physical production. But other reasons include more automation (such as tightening screws on a conveyor belt) and more workers who aren’t actually considered employees (such as the more than 1 million Foxconn employees who make Apple’s devices). It’s also because the stock market and shareholders now place a higher value on leaner companies that enable shareholders to reap the benefits of profits more than they once did.