Markets have a happy face on today, as they have for much of this year, as investors look forward to the promise of a second bail-out for Greece.

But it all hinges on agreement in debt talks between private sector creditors and the Greek government over the size of the haircut those creditors will have to wear on their Greek bond holdings.

Any voluntary debt restructuring is supposed to be comforting for markets and avoid a so-called credit event, which would trigger expensive pay-outs to credit default swaps holders. Pay-outs to CDS holders after Lehman’s default helped to deepen the 08/09 financial crisis.

But some bank analysts think such an event is still likely for Greece, as not all bondholders will play ball.

Credit Suisse analysts say:

We remain of the opinion that participation in the debt exchange is likely to fall short of the 75% level on which current debt/GDP targets are based. This would call for the enforcement of collective action clauses (CAC), triggering a non-voluntary restructuring. The CDS contract would be triggered as a result, most likely with negative implications for risk appetite. We expect the euro and risk-sensitive currencies to struggle again as we move through the PSI (private sector initiative) process.