I'm Selling a Company And Its Trademarks What Do I Need To Do

When you purchase a trademark, there is no requirement that you record the sale, but it sure is a good idea.  Why?  Take this example:

Owner A sells a trademark (and the underlying goodwill) to buyer B.  Buyer B never records the sale.  Owner A, feeling mischievous, then sells the mark again to buyer C.  If buyer C truly didn’t know about the sale to B, then C gets the mark and B loses out.  Had B recorded the sale, he wouldn’t be out of luck, and C wouldn’t have gotten the trademark.

As an aside, the sale of a trademark must be accompanied by the underlying goodwill – the bare sale of a trademark is ineffective.