Mutual funds like most equity assets are held in a separate entity from the broker, if the brokerage goes under they can’t liquidate those assets. SIPC would protect you if the brokerage did something shady.

SIPC insures up to $500k in securities and cash ($250K limit on cash) at member broker-dealers. There's no insurance against loss in value of the underlying asset; however, in the event of a bankruptcy of a broker-dealer, the first $500K of your assets are covered. The remainder would likely be fine as well, but you'd have to wait for some of the bankruptcy to play out.

As to OPM's original question, I would not worry about insurance limits at a firm lije Vanguard, Fidelity, T Rowe Price, etc.

Investments are not insured.

Only depository accounts are insured.

Mutual funds are never insured as they’re not bank deposits.

How does it work in an IRA account?

FDIC only covers $250k in bank deposits?

So if I have more than 250k in mutual funds at vanguard in an IrA, it’s sipc? Or should I move anything above 250k of my mutual funds to a different bank?