The new partnership between CIGNA (NYSE: CI) and Humana (NYSE: HUM) might be the best fit we've seen since a guy named Reese combined peanut butter and chocolate. And it'll be considerably healthier.

Both companies are in the health insurance business, but their clients are different enough that joining forces makes sense. Much of CIGNA's business is managing insurance for large employers, and Humana has a large offering of Medicare Advantage plans for retirees.

The new product will combine those two strengths by offering a single product for companies that offer insurance to both current employees and their retirees. The duo will split the profits evenly from the products that will be available in July. That is, as long as antitrust regulators don't have a problem with the partnership.

The partnership should help Humana close the gap with UnitedHealth Group (NYSE: UNH), which is the largest provider of Medicare Advantage thanks in part to its co-branding with AARP. Both companies face losses in membership in the coming years as government subsidies for the programs decrease.

For CIGNA, the partnership offers an additional way to monetize its clients. A complete package with a single point of contact could also help CIGNA compete for corporate clients against other large insurers like UnitedHealth, WellPoint (NYSE: WLP), and Aetna (NYSE: AET).

Health insurance reform has thrown a kink in health insurers' business plans. The changes will likely cut into margins, which companies will have to make up for with increased volume. Investors should be on the lookout for companies that can develop new products either through partnerships or acquisitions to help relieve the pressure on margins. So far, CIGNA and Humana seem like a yummy combination.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool owns shares of UnitedHealth and has a disclosure policy.