Some of these cases needed to be litigated; others maybe had less merit. Either way, Schlichter, Bogard went after some of the biggest companies in the world, including Boeing, Exelon, ABB and Edison International.

Plan sponsors will be relieved to know that Clark has since switched sides. He now works at the Lowenbaum Partnership, at an office not too far from his old one, representing sponsors' interests and helping beat back the Schlichters of the world.

Clark, presenting Thursday at the Center for Due Diligence conference here, has what could be viewed as not-so-bad news for sponsors.

Most of the major 401(k) plan service providers – including Fidelity, Nationwide, ING, Principal Life, John Hancock and MassMutual – seem to have been dragged into court at this point, he says. In other words, many of the cases so prominent a few years back are either resolved or close to finally winding down.

But Clark has bad news, too, in that some of these same plaintiffs' firms are now getting creative and more sophisticated, and returning to courtrooms with new allegations that will take more time and money to defend.  

Schlichter's firm, for example, filed a class action in March in North Carolina against Novant Health Inc., a nonprofit hospital system that operates across the Southeast.

The action, filed on behalf of 25,000 or so participants in two 401(k)s sponsored by Novant, alleges the plan fiduciaries violated ERISA by allowing excessive fees to be paid to the plans' broker and its recordkeeper.

In other words, this is a case in which the fees paid to sub advisors take center stage. That's a far cry from suing, say, Fidelity or Boeing. 

On the other hand, Clark says, there's plenty there to litigate.

"The $6 million allegedly paid in 2012 to the broker … amounts to about 40 basis points on $1.42 billion (in plan assets). If it ends up being that this was a case of the runaway train that can happen when providers are paid with uncapped revenue-sharing, we think this complaint should be a wake-up call to plan sponsors everywhere with similar setups," Clark wrote in his blog earlier this year.

The same can be said about the rash of suits filed this year alleging that Colorado-based Catholic Health Initiatives, among others, should no longer be considered exempt from ERISA, despite their church associations.

Some motions to dismiss these cases have been granted, but others haven't and so discovery is under way.

Clark says fiduciaries also should be ready to fight potential 408(b)(2) fee disclosure claims. Those regulations went into effect last year and are designed to force service providers to disclose all of the compensation they receive from a plan.

The courts in February dismissed a 408(b)(2) class-action against Morgan Stanley that alleged it received unreasonable compensation because of a "pay to play" scheme involving the plan's recordkeeper. But because the compensation had been disclosed, the court deemed the deal kosher enough.

"If the disclosure was less clear, as so many of the recent 408(b)(2) disclosures I review for my clients are, no dismissal may have been available, and Morgan Stanley would have been forced to defend themselves through lengthy and expensive discovery, motions practice, and possibly trial," Clark wrote in his blog.

In the meantime, there's also the potential for a new wave of stock-drop cases, in light of the U.S. Supreme Court's decision in June in Fifth Third Bancorp v. Dudenhoeffer. 

The decision wiped away a key "presumption of prudence" some courts had used to shield ESOP fiduciaries from liability in declining share-price cases. 

In short, there are still plenty of ways for plan sponsors and their advisors to find themselves in shark-infested waters. 

Clark, of course, is ready to help fish them out.