Tyler Cowen posts again on the theory that banks are using the ECB's new and broader facilities for arbitrage by buying risky sovereign debt, thereby driving interest rates down. There is another explanation for the fall in rates, see my comment below: The new ECB collateral rules dramatically increase the quantity of assets that banks can submit to the ECB in order to get ECB clearing balances. Bank loans are now allowed, so are lower quality ABS. This means that it is less likely that the national governments will have to guarantee local bank debt. This was a real problem in Greece and Ireland, for instance, for the local banks had run out of assets to submit to the ECB. Instead, banks were creating debts amongst each other and having the government guarantee these debts, before submitting them to the ECB as collateral. Since private non-marketable debt can now be submitted to the ECB, governments will no longer be required to covertly bail out their banks by guaranteeing intra-...