If a corporation purchases patent rights, are those records confidential or public?
In some jurisdictions, if an assignment is not lodged within a given period of time then the assignment may need to be re-executed to get it assigned on the register.
In some other jurisdictions, a fine is imposed if an assignment or exclusive license is not lodged within a given time-frame.
More commonly, it is not possible to institute infringement proceedings unless an assignment has been recorded at the IPO. The same applies to exclusive licensees (who are the only licencees recognised in most jurisdictions as having the right to sue for infringement).
Except for the unusual situation where an assignment has to be re-executed, there is no exclusion of rights for a failure to lodge an assignment and sometimes the new owner may choose not to register the assignment. This can be due to ignorance, laziness or a lack of funding. Sometimes, it is to obscure from the public who the true owner of the patent is.
Non-exclusive licenses of patent rights are often not allowed to be recorded on the patent register at all. These non-exclusive licenses are not generally made public as a result.
It is therefore a mixed bag of registrations (public) and non-registrations (generally kept confidential).