It is an increasingly familiar refrain. CFOs are retiring at the fastest pace in at least a decade—a generational changing of the guard that experts put down to factors including the increasing complexity of the role and the booming stock market.

One in six executives who left the CFO position at a U.S. public company in 2018 did so to retire, the highest share since at least 2007, according to an analysis of 12 years of regulatory filings by Audit Analytics for The Wall Street Journal.

Many CFOs leaving the role are simply reaching retirement age. Others point to new pressure from expanding job descriptions, which now often encompass oversight of human resources and information technology. Meanwhile, a rich array of advisory opportunities for seasoned executives may be tempting some into early retirement.

The market also plays a role: CFOs’ compensation often includes restricted equity grants, which in some cases can only be cashed out in full after retirement. A hot stock market has made that option more enticing. The S&P 500 stock index, which recouped losses suffered during the 2008 global financial crisis by 2013, has reached record highs this year.

Warning sign

Campbell Harvey, a professor at Duke University’s Fuqua School of Business, said the uptick in retirements could show that the executives overseeing American companies’ finances increasingly believe the long bull market will soon come to an end.

“It’s an intriguing market timing signal by people that are well able to assess the pulse and direction of the U.S. economy,” he said. “These executives are sitting on a pile of stock and it’s difficult to sell that stock as an insider, so when do you want to retire? Do you want to retire when the stock market is near an all-time high, or do you want to retire in the depths of the inevitable correction that might be a recession?”

A surge in deal activity has also been a factor. Last year was one of the busiest on record for mergers and acquisitions. Deals can trigger contract clauses that accelerate vesting requirements of restricted shares, giving CFOs an incentive to walk away, said Rhoda Longhenry, co-head of the financial officers practice at executive recruiter True Search.

The robust economy allowed Kenneth Pollak to retire from the CFO position at women’s apparel company Eileen Fisher Inc. in 2017 at the age of 66. “If the stock market didn’t come back, then I would say there was a good chance I would have worked a few more years,” he said.

Under pressure

CFOs are also tapping out because of escalating demands, recruiters said. CFOs once focused on regulatory compliance, accounting and reporting of financial results. Today, they are increasingly involved in setting strategy, finding and executing deals, and overseeing operations, technology, cybersecurity, talent management, human resources and risk.

Comparing the turnover rate for CFOs and CEOs provides some support for the idea that financial executives in particular are facing increased pressure at work. In 2009, the departure rates for CEOs and CFOs—for all reasons, not just retirement—were roughly the same, at 13.5% and 13.4% respectively, according to Audit Analytics. By 2018, the exit rate for CFOs had risen to 17.5%, compared with 15.2% for CEOs.