While his public profile may not compare to the likes of, say, News Corp.’s Rupert Murdoch or Bank of America’s Ken Lewis, Joel Gemunder boasts an executive pension that puts the longtime president and chief executive of Omnicare in a league of his own.

Gemunder, who has been with the Covington, Kentucky-based geriatrics pharmaceutical services company for more than 40 years—including 27 years as president and seven as CEO—has accumulated pension benefits worth $69.2 million, the largest such package at any company in the Fortune 1,000, according to an analysis of proxy filings conducted for Financial Week by compensation research firm Equilar.

Right below Gemunder, whose company ranks as the 386th largest in the Fortune 1,000, comes a collection of mostly notable names who have accumulated similar, albeit lesser, retirement benefits at blue-chip behemoths.

Robert Wright, the outgoing chief executive at General Electric, has an accumulated pension of $61.4 million, the second-largest of any executive, according to Equilar. His package is followed by the $60.3 million pension of James Mulva, chairman and CEO of Conoco-Phillips, with Murdoch’s $58.4 million pension and Lewis’ $52.4 million package rounding out the top five.

(These packages are generally composed of nonqualified, formula-based benefit plans, such as a supplemental executive retirement plan, or SERP, disclosed in the pension benefits section of a proxy, and do not include deferred compensation plans, noted Equilar senior researcher Alexander Cwirko-Godycki.)

Gemunder’s pension puts Omnicare in a peer group where it might not usually find itself, one that includes some of the largest corporations in the world. GE and Bank of America, for example, had revenue of $168 billion and $117 billion, respectively, in 2007.

While Omnicare is not a household name, it’s hardly a mom and pop shop: The company generated $114 million in earnings on $6.2 billion in revenue last year and employs more than 17,000 people.

It’s also not the only middle-market player with a CEO whose pension ranks as one of the largest.

For instance, W.R. Berkley chairman and CEO William R. Berkley has an accumulated benefit worth $37 million, which registers as the 12th-largest executive pension. The insurance company earned $743 million on $5.5 billion in revenue last year and was the 423rd-largest public company in the U.S.

The median value of accumulated pension benefits for a CEO at an S&P 500 company is $6.1 million, according to Equilar. Compensation experts say there’s a good reason why executives at midsize companies can find themselves staring at outsize pensions.

“Size and performance aren’t always the biggest factors in an executive’s pension,” said Peter Oppermann, an executive compensation consultant at Mercer. “Their years of service and compensation can often be the major drivers.”

That could explain why Gemunder, 68, and Berkley, 62, have built up such large benefits. Gemunder has 43 years of service at Omnicare, and Berkley founded his company 41 years ago.

In many cases, comp experts explain, executive pensions are calculated using a formula that multiplies a CEO’s years of service by a portion of their average compensation during a certain time period. Steven Hall, president of Steven Hall & Partners, a New York compensation consultancy, said companies tend to determine this average compensation level by looking at three to five years of an executive’s highest pay period—which can include both base salary and annual incentives.

“Indirectly, this can bring performance into the picture,” Hall said. “But pensions tend to be a reward for loyalty and service more than anything.”

The Omnicare proxy doesn’t divulge the exact compensation levels or formula used to calculate Gemunder’s $69 million in accumulated pension values, and a spokeswoman wouldn’t comment on anything related to his package that wasn’t disclosed in the filing.

The proxy does, however, break down the accumulated value into three parts: $66 million in an excess pension plan, $3.1 million in a “SERP II” and $1.5 million in a general pension plan that was frozen in 1994.

Gemunder earned a base salary of $1.67 million last year but did not receive a cash bonus, according to the proxy. Omnicare’s stock declined about 43 percent last year.

While there are still a good number of executives accumulating considerable pensions, Tim Bartl, vice president at the Center on Executive Compensation, expects the number of CEOs earning outsize retirement packages will soon begin to dwindle.

“As more companies are looking to pay for performance, they’re giving executives more equity rewards and incentives rather than guaranteed benefits,” he said, adding that when companies bring on new executives, many are now “evaluating whether or not these executive plans are a necessity.

Filed by Mark Bruno of Financial Week, a sister publication of Workforce Management. To comment, e-mail editors@workforce.com.