At these companies, CEOs far outearn workers

Soon, every U.S. public company will provide an illuminating factoid: the ratio between the pay of their CEO to that of the median worker.

That U.S. Securities and Exchange Commission regulation won't kick into effect until 2017, but that doesn't mean it's not possible to sift through the data now to sniff out which American businesses have the biggest ratios of all. While the lineup might change in two years, the companies now at the top tend to fall into two categories: health care and banks, according to an analysis from Bloomberg News.

There's one notable exception, however, and it's a supersize whopper. McDonald's (MCD), the world's biggest fast-food company, has the largest ratio: Its former CEO Donald Thompson earned 644 times the average worker's pay, Bloomberg found. While Thompson didn't have a particularly large CEO package when compared with other top executives, the large ratio stems from the huge ranks of low-paid workers who work the registers and kitchens at McDonald's restaurants.

Thompson, who stepped down from his role earlier this year, earned $7.29 million, while the average McDonald's worker at takes home $11,324, according to Bloomberg estimates.

Advocates of the new rule say it will help provide useful information to shareholders, while opponents say labor unions and activists could use it to shame companies and their executives.

Of course, it's not as if shareholders can't find out what a company's top executives are earning now. That information is provided annually by publicly traded companies in proxy statements.

The difference, however, will come from the additional information of illustrating how those pay packages compare with the paychecks of typical workers.

Already, it's clear that CEOs have been profiting handsomely during the past few decades, while average worker pay has stagnated. CEO pay has surged 937 percent from 1978 through 2013, compared with a 10.2 percent increase in a typical employee's paycheck during the same period, the left-leaning think tank Economic Policy Institute found in June.

CEOs in 2014 earned 296 times the average worker, compared with a 30-to-1 ratio in 1978, the EPI found.

The new disclosure rule will likely throw a new light on the disparity between CEO and worker pay. Some companies with the largest ratios are likely to be those where rank-and-file workers earn extremely low wages, such as in fast-food or retail industries. Financial companies, while paying relatively high wages to average workers, may still end up with large ratios because their chief execs tend to take home larger-than-average CEO pay packages.

The jury will be out for some time on how the disclosures could impact investors, according to compensation firm Equilar.

"The degree to which the CEO Pay ratio will influence investors remains to be seen, however. There's a lack of comparability across companies in terms of what's being calculated, so it's difficult to say what an 'appropriate' ratio should be," the company said earlier this month.

Below is the list of the top 11 companies with the biggest pay disparities between workers and CEOs, with the ratio in parenthesis, as compiled by Bloomberg.

1. McDonald's (644)
2. Community Health Systems (414)
3. Universal Health Services (329)
4. Priceline (294)
5. Carmike Cinemas (276)
6. Union Pacific (262)
7. Tenet Healthcare (242)
8. U.S. Bancorp (232)
9. JPMorgan Chase (222)
10. American Express (202)
11. HCA Holdings (198)