He says Whole Foods Market has "very low" turnover compared with other supermarkets and the retail sector in general. Plus, a much higher proportion of workers are full time, which he says adds to productivity.

Since 1992, when Whole Foods stock began trading, it is up roughly 21-fold, rising to a recent price at $61.30 from a split-adjusted $2.80 a share. The S&P 500 is up a little over threefold in the same time frame. Whole Foods also ranks as a consistently popular -- if expensive -- grocery store among consumers, and as one of the top places to work.

Why the pay gap matters to investors

Whole Foods' story suggests that the amount a company pays its employees relative to its top executives can give investors insights into how well the company's business and stock might do. So it should be helpful for investors when companies start reporting CEO-to-regular-worker pay ratios by the end of this year or early next -- assuming that provision of the Dodd-Frank financial reform act doesn't get taken out.

Several business groups and Rep. Nan Hayworth, R-N.Y., want to nix it, arguing that the pay ratio is immaterial for investors. They also say it is difficult for companies to calculate because they must incorporate the value of benefits as well as the pay numbers from W-2 forms.

After talking to Whole Foods, I'm not sure these protests stand up. The company links its success at least in part to that pay-ratio limit on most executive pay. So the pay ratio does seem relevant to investors.

Ehrnstein, at Whole Foods, also tells me it's not that much of a burden for his company to calculate pay levels for all employees. In fact, it already does so in annual reports made available to all workers.

An indicator you can use now

Whatever the fate of the Dodd-Frank CEO-to-worker pay reporting provision, you can already use existing pay information to help you make calls on stocks.

Many pay experts and Moody's Investors Service consider it a negative when CEOs make too much compared with the next level of executives. Outsized CEO pay can signal that a CEO has too much control over a company's board of directors. This might suggest the board is weak and not adequately looking out for shareholders. Excessive CEO pay compared with the next tier of top execs may also signal poor CEO succession planning at a company.

Moody's takes this pay gap so seriously that it can affect a company's credit rating.

How big is too big? Generally, any gap that has a CEO making more than three times the median of the next tier of top managers listed in a company proxy is a red flag.

Click here to become a fan of MSN Money on Facebook

Moody's won't say which companies have had their credit rating weakened because of this measure. But you can calculate the ratio yourself by comparing the pay reported for CEOs to the average pay for the next four executives listed in pay tables in company proxy statements. (You can find them here on MSN Money.)

One that stands out here is Viacom, where Dauman's $84.5 million was almost eight times the median of $10.6 million earned by the executives right below him, says Paul Hodgson of GovernanceMetrics International, an investment risk and governance research firm.

An even more extreme example is the homebuilder NVR (NVR, news), where CEO Paul Saville's $13.5 million in pay last year was almost 24 times the median of the top execs right below him, says Hodgson. Saville's pay was also 782 times the $39,470 earned by the typical carpenter last year -- a pay gap well above the average for S&P 500 companies. The housing sector might be in the doldrums, and a lot of carpenters couldn't even find work. But Saville still got big bucks.

At the time of publication, Michael Brush did not own or control shares in any company mentioned in this column.

Michael Brush is the editor of Brush Up on Stocks, an investment newsletter. Click here to find Brush's most recent articles and blog posts.