Willis's cancellation of a $300m bond issue last week has led to speculation that the broker is planning to announce a merger deal.
Gimme Credit debt analyst, Kathleen Shanley, told Dow Jones Newswires that "I suspect some kind of news is in the offing".
She said the cancellation by Willis's North American subsidiary was "highly unusual for an investment grade issuer, though it occasionally happens in high yield".
Shanley added: "Willis is certainly small enough to be a target, and consolidation would be one way to reduce costs in a competitive industry."
