I interviewed at XJT yesterday, and they asked me the same question. My answer was that as my wife and I near the age where we want to settle down and have kids, I want to be with a stable company. My current company has no future. Management has outright said that they don't know where the company will be after 2009. They said they know that ML has a plan for us, but they're not aware of what it is. I can't take such an irresponsible position when trying to support my family, and for that reason I'd like to move on.
They liked that answer. I got the job.