Banking system outgrew its lender of last resort
The three Icelandic banks grew to roughly ten times Iceland's GDP, far beyond what the central bank and state could backstop in a run. Because the banks' liabilities sat largely in foreign currency, the Central Bank of Iceland could not print its way to rescuing them, so the collapse was a structural mismatch between bank size and sovereign capacity, not only a failure of individual bank management. This is the author's framing, and as Kaupthing's chief economist he has an interest in stressing systemic over firm-level causes.