I'm not sure what a "realistic" chance of failure is, but if it were a foregone conclusion that the HD trial will be successful, why is anyone waiting to finalize the partnership? Coming at from another angle, in how many cases have investors in small biotechs convinced themselves that that trial results were sure to be favorable yet the unexpected somehow happened. Obviously, the skill lies in distinguishing those cases where the chance of failure really is small from those where it is not, but I think the conviction that success is inevitable creates bad karma.