right off their financial statements off their last annual...

right off their financial statements off their last annual reports , ANZ $47,702M Credit default swaps NAB is about $24B from memory, these are notional ANZ have them netted as a 300M asset , in a global derivatives meltdown though where the counterparties start failing notional can start looking actual depending on the scenario, refer to my posts on the ANZ thread "15 place your bets" for a proper description of the scenarios
that could lead to this, basically a monoline insurer fails then a counter party fails and it becomes impossible to replace the swap cover at the same time as the underlying debt fails.

its not something that was previously considered very likely but things are changing very fast

lets underline here that no one outside ANZ really understands the true risk underlying their CDS hedge book, we can only speculate with the facts we do have