Good thing someone started a thread about this because it hasn't been discussed at all in the last two years.
Tommy was dropped by Nike a few years ago, I think it was around the time they dropped Hewitt. At various times since then he has signed with Asics, K-Swiss, Limited Sports, and I think there was one other company in there somewhere. Not sure what happened with Limited, but he lost his KSwiss and Asics contracts because he kept wearing other clothes and shoes in practices (and a few matches).
Pros should stop wasting money on coaches and doctors and just read the experts on this forum.