404(c) Protection with only brokerage accounts?

Can participant accounts be protected under 404(c) when the only investment vehicle is brokerage accounts and the Trustees offer no suggested funds to satisfy the requirement of diverse asset classes available?

If other conditions for an ERISA § 404(c) defense are met, the key question is:  Does the brokerage account “[p]rovide[] a participant or beneficiary an opportunity to choose, from a broad range of investment alternatives [as 29 C.F.R. § 2550.404c-1(b)(3) provides], the manner in which some or all of the assets in his account are invested”?  https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XXV/subchapter-F/part-2550/section-2550.404c-1

Whether a particular brokerage account meets that call might involve questions of law, questions of fact, and mixed questions of law and fact.

Even if an ERISA § 404(c) defense applies, it does not relieve a fiduciary from liability to the extent that a loss results from a cause other than the directing person’s exercise of control.

If a governing document grants a fiduciary a power to select investment alternatives, a fiduciary who selects only brokerage accounts might consider whether she could defend her reasoning for excluding other investment alternatives, and whether she could prove she acted “with the care, skill, prudence, and diligence” ERISA requires and for the exclusive purpose ERISA requires.

I believe the short and technical answer is yes.  Whether it is possible in practice to comply with the notice requirements is up for debate, but I guess you could say that about a lot of pension stuff.

Well, I guess the plan doc DOES say the Employer "intends" to comply with 404(c).  (Similar language in the SPD.)

It's not dealing with 404(c), but the DOL has published a less than favorable opinion of self directed plans that only provide a brokerage window in their fee disclosure guidance.  From FAB 2012-2R Q&A 39:

"... Nonetheless, in the case of a 401(k) or other individual account plan covered under the regulation, a plan fiduciary's failure to designate investment alternatives, for example, to avoid investment disclosures under the regulation, raises questions under ERISA section 404(a)'s general statutory fiduciary duties of prudence and loyalty. Also, fiduciaries of such plans with platforms or brokerage windows, self-directed brokerage accounts, or similar plan arrangements that enable participants and beneficiaries to select investments beyond those designated by the plan are still bound by ERISA section 404(a)'s statutory duties of prudence and loyalty to participants and beneficiaries who use the platform or the brokerage window, self-directed brokerage account, or similar plan arrangement, including taking into account the nature and quality of services provided in connection with the platform or the brokerage window, self-directed brokerage account, or similar plan arrangement."

Field Assistance Bulletin No. 2012-02R (1) | U.S. Department of Labor (dol.gov)