It would be remiss of the rating agencies not to have acted i.e downgraded, if their models suggested, at best, a 30% recovery on Greek debt. Ultimately, it's not the banks determining the rate of interest on Greek govvy debt, but the auction participants. Greece recently launched debt issuances in the states and the Europe, so it's fair to say the yield on 10-year debt is representative of wide investor opinion, rather than maverick speculators or greedy banks. Not many people wanted to take on the debt, so the yield rose till people bit. It's worth remembering Greece are running a budget deficit of over 12%, with short term debt needing re-financing far more often than other countries. It appears to have no credible means of bringing down the deficit, let alone eating into the massive stack of debt in its name.