There are a number of mechanisms besides the FDIC that are commonly used for depositors of this scale. You can even buy your own insurance, if nothing else.

From whom? A search for "bank failure private insurance" kept talking about FDIC and sometimes SIPC.

CDARS is one system. A whole bunch of different systems have been mentioned scattered throughout these comments. But the bottom line is that if you really need to know what the options are, you really need to talk to a financial advisor with expertise in this level of business. They'll know what all the options are.

This is a rather specialized and technical area of finance, and like most technical areas, I imagine it's hard to search for unless you know the magic terms and jargon to search for.

>From whom?

Lloyds and AIG will insure just about anything, they'll happily protect $x million or billion for a nominal fee.

This isn't a viable solution; AIG almost went under in 2008.