Total median CEO pay, excluding pensions, at large capital U.S. companies grew just 3.9 percent, the lowest increase since the financial crisis of 2008. That’s the conclusion drawn in a new study by ISS Corporate Solutions, a subsidiary of Institutional Shareholder Services, a leading proxy advisory firm.

The analysis—of CEO pay at S&P 500 companies reporting their annual financials through April 15, 2016—found that median pay stands at just under $10.5 million, compared with roughly $10.2 million in fiscal 2014. Including pension allocations, the median CEO pay raise was only 0.1 percent.

“Muted pay increases may reflect increased market uncertainty caused by energy price fluctuations and, more broadly, by spikes in market volatility indices that began to occur more frequently in the fourth quarter of 2014,” says John Roe, head of advisory at ISS Corporate Solutions. “Some compensation committees responded by being more conservative in their increases, and focusing those increases in performance-based awards, to encourage better pay-for-performance outcomes.”

The largest driver of the diminished year-over-year pay changes was smaller allocations to CEO pensions, the study says. These pension allocations measurably declined in 2015, in aggregate falling by more than 57 percent year-over-year, mostly due to large one-time adjustments that companies took in 2014 due to changes in actuarial tables, combined with lowered interest rate expectations. Pension allocations across those 280 S&P500 companies studied dropped by $262 million.  These decreases almost entirely offset increases in other areas of CEO pay.

Non-equity incentive payments, typically a barometer for compensation committees’ evaluation of annual performance, dipped modestly but far less so than overall market performance.  These payments, typically annual cash awards made to reward the realization of predefined performance objectives, were down roughly 1.7 percent in fiscal 2015 compared with 2014, in a year where the S&P 500 index performance fell 12.4 percent.

For S&P 500 CEOs, base salary increases were roughly in line with those for rank-and-file employees. The median base salary raise for CEOs from 2014 to 2015 was 2.2 percent, lower than the median 3.0 percent raise forecast for U.S. company workers. Discretionary bonuses continued their retreat, paid out by less than 12 percent of these companies and accounting for only 2.3 percent of S&P 500 CEO pay.

As in past years, stock grants made up for some of the modest base salary increases, with the median S&P 500 CEO receiving 5.8 percent more value in stock grants during fiscal 2015 than in 2014. The use of stock options by the compensation committees of S&P 500 companies, however, continued its slow decline. Decreases in option grants offset more than half of the increases associated with full value stock grants.  Combined with a trend to maintain a balance of time-based and performance-based equity awards, this overall led to pay packages that are generally more favored by investors.

Across industries, companies in the Health Care Equipment & Services and Real Estate groupings saw double-digit gains in median CEO pay of 12.8 and 11.7 percent, respectively. By location, median CEO pay also saw double digit gains in the San Francisco Bay Area and Boston (10.8 and 10.5 percent).

The analysis focused on median year-over-changes, rather than changes in the median, and compared only CEOs that were in place for full-year 2014 and 2015 and excluded “unusual” CEO situations that may cause pay abnormalities, such as dual-CEOs. The study looked at all companies filing after July 1, 2015, as having disclosed their 2015 pay.