Women still account for a small percentage of CEOs at the largest publicly traded U.S. firms, but some of those who've made it to the corner office are earning much more than their male counterparts.
Executive data firm Equilar did a study on CEO pay at the 100-largest companies (by revenue) that filed proxy statements by April 1, and it found that women at the helm of these firms earned significantly more than their male peers for 2015.
But it's a tiny group: Last year, just eight women served in the top position at firms in the study. However, on average they earned almost $23 million, compared to an average of nearly $15 million for male CEOs. Compensation includes base salary, yearly bonus, stock and options awards, and any other perks.
The eye-popping pay for female CEOs in the study reflects that, by and large, they're leading some of the most successful companies in America, according to Dan Marcec, director of content at Equilar.
"The fact remains that out of 100 CEOs, only eight are female, and that's a very small number. But they have been very successful," said Marcec, adding that executive compensation is more closely tied today to company performance than it was just a few years ago.
Three of the eight female CEOs in the study hail from the tech world, where compensation tends to be relatively high compared to other sectors. That's partly a result of the intense competition for talent in the sector.
Safra Catz, co-CEO of Oracle (ORCL), is the highest-paid female CEO in the Equilar study. She and fellow Oracle CEO Mark Hurd were each awarded $53.2 million in 2015, putting them atop all the executives in the study.
Oracle, which tends to be a highflier each year in terms of executive compensation, had a total shareholder return of 5 percent in 2015, beating the S&P 500 index, which had a total return (including dividends reinvested) of nearly 1.4 percent last year.
Virginia Rometty of IBM (IBM) and Meg Whitman of Hewlett Packard Enterprise (HPE) are also among the highest-paid female CEOs in the study, with compensation packages valued at nearly $20 million and about $17 million, respectively, for 2015.
Rometty's pay increased by 10 percent over 2014, but IBM's total return declined by 11 percent, according to Equilar. Meanwhile, Whitman's pay was down 13 percent from the prior year, and HP suffered a 23 percent decline in total return.
"IBM and HP are really trying to fight to keep talent at their firms," said John Trentacoste, a managing director at consulting firm Farient Advisors. "There has been a huge brain drain from blue-chip companies to smaller, more-nimble competitors," he added.
Interestingly, the Equilar study also found that CEO pay still appears to be climbing, despite stock market volatility and lower revenue at many large companies, such as those in the energy sector. Median pay for all executives in the Equilar study rose 3 percent in 2015.
Lynn Good, CEO of Duke Energy (DUK), got a whopping 34 percent increase in compensation (to nearly $11 million), despite the fact that company's total shareholder return fell by 11 percent, according to the study.
Marcec of Equilar said companies tend to take a long view when setting CEO pay, basing it on multiple years' worth of performance. Compensation committees, he added, also understand that CEOs can't control all factors that influence performance, such as the price of oil.
"Shareholder returns have been up over the long term, and that's what CEOs are judged by," said Marcec. "Chief executives can't control all market factors, and companies want to account for that so they can keep their CEOs pushing forward even during the hard times."
Joining these four female CEOs were PepsiCo's (PEP) Indra Nooyi ($22 million), General Dynamics' (GD) Phebe Novakovic ($20 million), Lockheed Martin's (LMT) Marillyn Hewson ($20 million) and Mondelez International's (MDLZ) Irene Rosenfeld ($18 million).