With expanded 401(k) fee disclosures to employees this summer likely to focus even more attention on retirement plans, plan sponsors may want to review their service providers and the burden of fiduciary liability.

While the Employee Retirement Income Security Act (ERISA), which governs workplace retirement plans, mandates that plan sponsors get outside expert help when they don't have enough expertise in-house, that doesn't relieve companies of their fiduciary responsibility. Outsourcing requires vigilance, too.

Consider the cautionary tale of several small plans that entrusted fiduciary responsibility to someone once considered a stalwart in the field.