Sony apparently forgot to file a request to maintain its claim on the Bloodborne brand.
Trademarks are important. So important, in fact, that company's will sometimes go to seemingly silly lengths to protect them. That being the case, you'd probably expect that a company the size of Sony would do the basic maintenance required to keep its trademarks safe and secure. In the least, you'd think they'd make sure the trademark was active the day before their next big game releases.
Not so, it would seem, with Bloodborne. While the game released exclusively today on the PS4, Sony no longer holds the trademark for its brand. While the company has offered no official reason for abandoning the trademark, the USPTO's website states that it was due to a failure on Sony's part to file a Statement of Use or Extension Request. In other words, Sony probably just forgot to do its paperwork.
It's worth noting that this isn't the first time this has happened this year. Just last month Sony accidentally abandoned the trademark for The Last Guardian. This, understandably, prompted many to assume that the long in-the-works game had been cancelled despite fairly recent claims from the company that it was still in full development. According to the NeoGAF thread that uncovered this latest lapse, these errors mostly stem from the departure of the company attorney who previously handled the trademark work for both The Last Guardian and Bloodborne. In the case of The Last Guardian, Sony quickly filed another request to reclaim the game's trademark. We feel safe in assuming it will do the same in this case as well.