The cash in your brokerage account would be covered by sipc, not fdic.
Sipc does have its limits for what it guarantees, I guess anything over that would be based on recoveries in the event of a default:
https://www.firstrepublic.com/insights-education/sipc-vs-fdi...
The question is where they’re investing the float.
Investments of float accounts for a big proportion of brokerage profits (along with payment for order flow):
> 57% of Schwab’s revenues are from net interest. The firm could literally give away every other service; discount the mutual fund fees to zero, do away with commissions, etc etc, and they would still be profitable.
> Schwab isn’t even the leader among discount brokerages in dependence on net interest. That would be E*TRADE, at about 67% of revenues. Interactive Brokers makes 49% and TD Ameritrade 51% in the segment.
https://www.kalzumeus.com/2019/6/26/how-brokerages-make-mone...
Stock trading commissions in USA for a while have basically been a scam and it’s only because Robinhood came along that that source of revenue is gone to $0. That might result in more risk-taking on the float side.
Schwab is not going under. Feds would never allow it. This is an overreaction, and honestly I'd start thinking about buying Schwab stock