Meta's internal codename for its next frontier large language model after Muse Spark, Watermelon has driven trader focus through scaling claims and a narrow release window. Alexandr Wang stated in a July 2026 town hall that the model—still in training and using roughly 10x the compute of its predecessor—had reached parity with OpenAI's GPT-5.5 on internal benchmarks, though those scores remain unnamed and unverified externally. Mark Zuckerberg teased the project publicly in September, but Meta Connect passed without a launch or weights release. Internal documents cited by The Information pointed to an October 2026 target, with recent reporting noting accelerated integration plans following Muse stabilization; prediction markets now cluster heavily around a mid-to-late October debut amid ongoing pre-training progress.