There are alternative 401K plans where you can hold things like real estate, gold, etc. in your 401K account ... though if it's an employer plan, I doubt they'd allow those options.  Mostly people use these for tax shelters since traditional 401Ks are tax-free up front.  If you put your house in your 401K, for instance, you can also effectively put money in there that you spend on maintaining it, remodeling, repairs, etc.  That money then would be disbursed to the contractors, supply companies, etc. from within the 401K account and therefore escape all taxes.  It's a secret way to take advantage of 401K regulations to turn them into tax shelters.

I used to work as a software developer for this company.
https://invest.trustetc.com/gsre-sdira

There's very little oversight of the accounts, so people are basically using these account to launder money through them.

Shockingly low margins on purchases of CostCo's gold bars: https://www.zerohedge.com/commodities/pamp-it-costco-selling-200-million-gold-bars-month-wells-fargo-says

I avoid proprietary non-government precious metal coins and products, preferring instead to only buy well-recognized numismatic bullion coins… BUT… a 2% margin?  THAT is tempting.

I saw a lot of the data in that company’s systems, and there were clear cases of tax evasion and money laundering / fraud going on.  But the company looked the other way because these are “self-directed” accounts so they don’t really care.  In some cases there’s a very fine line between with some of the activity.

One example is that in at least 50% of cases (I ran queries), there was no proof that certain real estate held in these funds actually existed.  Company was supposed to hold the deed, but they never enforced requiring that it be sent in.

No doubt. I'd bet the non-trust filings are similarly full of evasions.
Bottom line: End the (((fed)))!

Jєω BANKSTERS: https://archive.is/u4MwH also: https://web.archive.org/web/20230328185456/judaism.is/banksters.html