[eru]

Yes. To oversimplify, capital is what's left after you take all your assets and subtract all your debt.

So you take all the investments that the bank has made (loans, but also their brand value, the office buildings they own and operate in, etc) and subtract all the deposits and outstanding bonds etc, and what's left over is their capital.

Another related way to measure that is to look at total market capitalisation. (But market cap makes economic sense, that's not the definition of loss absorbing capital that's used in the regulations.)