Quote below is from the Fidelity "Brokerage Handbook", I've had my
Fido accounts for so long that I don't recall if I previously selected
FCR, or if that what the default when I opened out accounts.
What are the investment options for my Core account?
For Retirement accounts like IRAs, your only Core account option is
Fidelity Cash Reserves, a money market fund1.
For Brokerage accounts, your Core is an interest-bearing cash account
called FCASH, unless you specified otherwise when you opened your
Fidelity Account. You can only change your Core account at any time by
calling a Fidelity Representative at 1-800-544-6666. You cannot change
your Core account online. Your other choices are:
* Fidelity Municipal Money Market Fund (FTEXX), a federal municipal
mutual fund seeking income free from federal income tax.1, 2
* Fidelity Tax-Free Money Market Fund (FMOXX), a federal municipal
mutual fund seeking to provide income free from federal income taxes
and the federal alternative minimum taxes.1, 3
* Fidelity state municipal money market funds, which seek high
current tax-free income1, 2 for residents of AZ, CA, CT, FL, MA, MI,
NJ, NY, OH or PA
Although you can have only one Core account, you can still invest in
other money market funds.