"SIPC protection is limited. SIPC only protects the custody function of the broker dealer, which means that SIPC works to restore to customers their securities and cash that are in their accounts when the brokerage firm liquidation begins.
SIPC does not protect against the decline in value of your securities. SIPC does not protect individuals who are sold worthless stocks and other securities. SIPC does not protect against losses due to a broker’s bad investment advice, or for recommending inappropriate investments.
It is important to recognize that SIPC protection is not the same as protection for your cash at a Federal Deposit Insurance Corporation (FDIC) insured banking institution because SIPC does not protect the value of any security."
So if the $1.00 per share price of the Money Market Fund goes to $0.99, you’ve just taken a 1% loss, and SIPC does not owe you anything.
If the Money Market Fund is full of rotting, reeking {fill in the blank} and it goes to $0.00 per share, and you take a 100% total loss, SIPC does not owe you anything.
But wait… the quote above mentions “cash”, isn’t a Money Market Fund the same thing as cash? No it is not… a Money Market Fund is considered an investment. True cash would be the default cash sweep at Schwab, or FCASH at Fidelity. Fidelity Cash Management and Fidelity HSAs use truly FDIC insured cash options, however, by sending your money to several “program banks”.
Caveat Emptor! FDIC and SIPC insurances are not the same.