IP blocks are "licensed", not sold. These licenses can be transferred, but only under certain strict conditions.
The ARIN CEO stated [1]
«As you may be aware, ARIN is the Regional Internet Registry (RIR) responsible for Internet number resource management for Canada, United States, and parts of the Caribbean. In keeping with the policies developed by the community in this region, there are two possible ways to transfer IPv4 number resources to another party (via merger & acquisition transfer or via specified transfer), and these are detailed in section 8 of the Number Resource Policy Manual on the ARIN website at <https://www.arin.net/policy/nrpm.html>;
It is important to note that transfer of number resources via either method must be to another party that can demonstrate corresponding need. ARIN's registration services department can assist with this determination in advance or at the time of transfer. ARIN reiterates the importance of veracity in transfer requests and supporting documentation as fraudulent information can result in resource revocation.»
NRPM section 8 [2] says
«Number resources are nontransferable and are not assignable to any other organization unless ARIN has expressly and in writing approved a request for transfer.
…
It should be understood that number resources are not 'sold' under ARIN administration. Rather, number resources are assigned to an organization for its exclusive use for the purpose stated in the request, …»
Older blocks allocated directly from IANA have different conditions attached to them that may render the transfer of the these licenses simpler or harder.
IP blocks are "licensed", not sold. These licenses can be transferred, but only under certain strict conditions.
The ARIN CEO stated [1]
«As you may be aware, ARIN is the Regional Internet Registry (RIR) responsible for Internet number resource management for Canada, United States, and parts of the Caribbean. In keeping with the policies developed by the community in this region, there are two possible ways to transfer IPv4 number resources to another party (via merger & acquisition transfer or via specified transfer), and these are detailed in section 8 of the Number Resource Policy Manual on the ARIN website at <https://www.arin.net/policy/nrpm.html>;
It is important to note that transfer of number resources via either method must be to another party that can demonstrate corresponding need. ARIN's registration services department can assist with this determination in advance or at the time of transfer. ARIN reiterates the importance of veracity in transfer requests and supporting documentation as fraudulent information can result in resource revocation.»
NRPM section 8 [2] says
«Number resources are nontransferable and are not assignable to any other organization unless ARIN has expressly and in writing approved a request for transfer.
…
It should be understood that number resources are not 'sold' under ARIN administration. Rather, number resources are assigned to an organization for its exclusive use for the purpose stated in the request, …»
Older blocks allocated directly from IANA have different conditions attached to them that may render the transfer of the these licenses simpler or harder.
[1] http://mailman.nanog.org/pipermail/nanog/2011-August/038888....
[2] https://www.arin.net/policy/nrpm.html#eight