Return-to-office mandates at some of the most powerful tech companies — Apple, Microsoft and SpaceX — were followed by a spike in departures among the most senior, tough-to-replace talent, according to a case study published last week by researchers at the University of Chicago and the University of Michigan.

Researchers drew on resume data from People Data Labs to understand the impact that forced returns to offices had on employee tenure, and the movement of workers between companies. What they found was a strong correlation between senior-level employees departing directly after a mandate was implemented, suggesting these policies “had a negative effect on the tenure and seniority of their respective workforce.” High-ranking employees stayed several months less than they might have without the mandate, the research suggests — and in many cases, they went to work for direct competitors.

At Microsoft, the share of senior employees as a portion of the company’s overall workforce declined more than 5 percentage points after the return-to-office mandate took effect, the researchers found. At Apple, the decline was 4 percentage points, while at SpaceX — the only company of the three to require workers to be fully in-person — the share of senior employees dropped 15 percentage points.

“We find experienced employees impacted by these policies at major tech companies seek work elsewhere, taking some of the most valuable human capital investments and tools of productivity with them,” said Austin Wright, an assistant professor of public policy at the University of Chicago and one of the study’s authors. “Business leaders should weigh carefully employee preferences and market opportunities when deciding when, or if, they mandate a return to office.”

Technology is an industry “where the discourse over the return to office was most heated,” said David Van Dijcke, a researcher at the University of Michigan who worked on the study. Microsoft, Apple and SpaceX play an outsize role in the sector — collectively they represent more than 2 percent of the tech workforce and 30 percent of the industry’s revenue, according to researchers — and their office policy “sets the precedent for the wider debate around the return to office,” the study’s authors wrote.

Those three companies also were among the first Big Tech firms to pursue return-to-office mandates in 2022, allowing researchers to separate the effects of mandates from the widespread tech layoffs that rocked the industry later in the year, Van Dijcke said.

Microsoft declined to comment on the research or its return-to-office policies, and SpaceX did not respond to a request for comment from The Washington Post. But Apple spokesman Josh Rosenstock criticized the study as work that draws “inaccurate conclusions” and “does not reflect the realities of our business.”

“In fact, attrition is at historically low levels,” Rosenstock said.

Apple, Microsoft and SpaceX differ “markedly” in their corporate cultures and lines of business, and took different approaches in their return-to-office policies. Yet the similar effects of the RTO mandates found by the researchers suggest that “the effects are driven by common underlying dynamics,” the authors wrote.

“Our findings suggest that RTO mandates cost the company more than previously thought,” Van Dijcke said. “These attrition rates aren’t just something that can be managed away.”

The tug-of-war over offices has been locked in a stalemate for roughly a year: Office occupancy data tracked by Kastle Systems shows that the national average across the country’s top metro areas — including New York City, Washington, D.C. and San Francisco — has hovered stubbornly around 50 percent of pre-pandemic levels since early 2023.

A spike in departures of senior employees following return-to-office mandates could reflect the “double-pinch” they inflict on managers, who have to deal with the policy’s effects on the teams they lead and in their own lives, said Christopher Myers, associate professor of management and organization health at Johns Hopkins University, who did not work on the study.

He compared it to leading employees amid layoffs or wage stagnation.

“It’s a change to the work structure, sure, but it’s also just a hit to morale,” said Myers, who is also a scholar with the Academy of Management. Maybe managers leave shortly after mandates, he posited, “because it’s easier to manage a team that’s happy.”

Tech executives have extolled the values of in-person work, citing benefits to connectedness and innovation. CEOs such as OpenAI’s Sam Altman, Meta’s Mark Zuckerberg and Tesla’s Elon Musk have criticized remote work’s effects on company culture and productivity. In an April interview with CNBC, Nike’s CEO John Donahoe attributed a slowdown in innovation at the company to remote work, saying that “it’s really hard to do bold, disruptive innovation, to develop a boldly disruptive shoe on Zoom.”

Executives have not provided much evidence that a return to office actually benefits their workforces, said Robert Ployhart, a professor of business administration and management at the University of South Carolina. For example, there’s nothing pointing to a widespread drop-off in productivity as hybrid work has increased, he said.

“The people sitting at the apex may not like the way they feel the organization is being run, but if they’re not bringing data to that point of view, it’s really hard to argue why people should be coming back to the workplace more frequently,” Ployhart said.

Senior employees, Ployhart said, are “the caretakers of a company’s culture” and having to replace them can have negative effects on team morale and productivity.

“By driving those employees away, they’ve actually enhanced and sped up the very thing they were trying to stop,” Ployhart said.

Although the study focused on three companies, its findings broadly reflect the impact of return-to-office mandates on workforces across the country, according to Ployhart, who is also a scholar with the Academy of Management. Companies are still struggling to adapt to a landscape fundamentally altered by hybrid work.

“We really have a very fragmented world, and these one-size-fits-all policies tend to struggle to be successful when there’s so much nuance in the way we work,” Ployhart said.