The causes are most likely structural. In 1950, a typical share of stock in United States public markets was held for eight years. Since 2006, the average share of stock has been held for less than a year. This shift is largely because of the spread of technology-enabled trading and the rise of activist hedge funds looking for short-term profits. And it may be changing how the most important companies in America are managed. A 2006 study conducted by economists at Duke University found that 78 percent of executives at public companies said that they would sacrifice long-term economic value for a short-term lift in share price.

They are under intense pressure to do so. In 2018, the median tenure for chief executives fell to a historic low of five years. Wall Street analysts dissect corporate quarterly earnings scorecards like never before, leading executives to focus more of their efforts on hitting near-term targets. This means executives may be increasingly unable, not just unwilling, to pursue long-term value-creating activities like investing in research or training for their employees.

Instead, they are being evaluated by investors on their ability to produce immediate financial value, almost always in the form of value-extracting activities such as cost-cutting, price increases, share buybacks or other forms of financial engineering. This behavior is at least partly to blame for the unethical business practices that have dominated recent news.

Unfortunately, the problem of short-termism isn’t confined to public companies whose share prices are at the mercy of the stock markets. A willingness to gamble long-term reputation and growth for a short-term valuation bump is now a hallmark of private companies in Silicon Valley as well. The ethos of move fast and break things, which has defined a generation of start-ups, is not the mantra of long-term investors. It is the clarion call of speculators, who fully expect to get out before any of their own things can get broken.

The causes of short-term behavior in private markets mirror the story in public markets. Ownership of America’s privately held companies has shifted away from long-term operators, like family-owned businesses, to third-party investors — venture capital and private equity firms like SoftBank and TPG. Since mid-2009 investors have allocated $5.8 trillion to global private equity alone.