Via Zero Hedge (I'd love to read the full Daily Observation piece, if anyone has access to it):
We estimate that the Spanish banking system only has a few hundred billion euros left in eligible collateral. That means that some of the weaker banks are likely already getting close to a point where their collateral is exhausted. (We think this reality is the reason why we are seeing a number of legal changes in Spain that look like an attempt to scrounge up a bit more capital). if Spanish banks run out of ECB collateral, then the Spanish central bank would likely need to turn on its own ELA. The potential magnitude of such an operation would dwarf the nationalized money printing to date.
Spanish balance sheets can probably support about €800 billion of borrowing from the ECB. Between the ECB and privately secured funding, mostly foreign interbank, Spanish banks are already borrowing about €500 billion, and if private secured funding was pulled, this borrowing and related collateral could be shifted to the ECB. So we think about the remaining capacity to borrow as the total collateral borrowing capacity (€800 billion) less what is pledged to both the ECB and private lenders (€500 billion), or about €300 billion. However, this almost certainly overstates Spanish banks' collateral cushion because there are strong banks such as BBVA and Santander that probably have ample capacity and weaker banks that are likely much closer to being tapped out.