https://www.interactivebrokers.com/en/accounts/sweep-program...

https://www.cnb.com/business-banking/accounts/savings/bank-d...

https://www.wellsfargo.com/investing/cash-sweep/

Of course if those banks are depositing to the same 10 banks then you're really protected at 10x...but, well much better than 250k? I'm going to guess it's called a "Sweep Program" but I'm no finance expert. I know of this because it's common for brokerage account to do this - as very often, you'll have more than $250k in cash if you're doing active trading.

It generally looks transparent and like it's just in your chosen bank. (Though if you want laddering, etc, you do need to plan).

If you have a lot of cash, you buy T-Bills and other instruments with some of it.

And yes, you have some risk remaining, of some of the cash disappearing. But with diversification and insurance, it is negligible.