I think I can answer you question without having to do any specific research (pulling from my experience/knowledge of finance merger/acquisitions). From the nature of the deal (i.e., merger) in which perhaps stock is swapped there is no actual transaction of assets, rather an exchange of ownership (i.e., equity). Typically all the assets (including intangible assets (aka IP) would remain with the newly formed merged company. Now if this had been an acquisition of assets (asset deal vs. stock deal) then the IP could have or could have not been transferred. one would think if certain IP would not have been sold in this case the seller would later use this IP or sell it to a 3rd party.
I think we would have heard something by now if the IP was sold to any other 3rd parties.
Of course I could be wrong, but i think this is the more likely scenario.
Regards,
Chris
EDIT: Sorry i read your other post and did some further research, I didn’t find anything about any selling off of t Sierra IP in the filling by Blizzard Activision. Being a public company i beleive a transaction of this nature would have to be disclosed unless it was not considered material.