Kanye West has “rebranded” himself as Ye. Ye had been his nickname for a while. Earlier this year he said “I believe ‘ye’ is the most common word in the Bible, and in the Bible it means ‘you'”. Since the company behind Kanye West (Mascotte) has registered the name Yeezus as well, Kanye has serious plans.
Kanye West has not yet registered Ye as a trademark. Remarkable as Kanye West has registered many other trademarks and thus recognizes the importance of a trademark. Kanye is not the first and will also not be the last to forget to check his new name for availability and to register it. As trademark searches and registration take some time, it is advisable to take sufficient time for the introduction of the new name. Of course you do not want to be confronted with the (older) rights of a trademark owner. Caution is particularly recommended in case of a worldwide celebrity such as Kanye West (or in case of a well-known company).
It could be that the trademark has already been filed by a cover company who will transfer the trademark to Kanye West later on, a smart trick. Another trick, which we saw by Apple, is that a trademark is filed in an inaccessible trademark register first. An other way to keep trademark applications under the radar.