AI startup Baseten is on the verge of securing a massive $1.5 billion funding round, which would value the company at $13 billion, according to the Wall Street Journal. This comes just five months after the company announced a $300 million Series E at a $5 billion valuation, which itself followed a $150 million Series D raised nine months prior. If this latest deal is completed, it would mark a staggering 160% increase in valuation in under six months.

However, the Journal notes that this round uses a split-pricing structure—a tactic some startups employ to inflate their headline valuation and make lead investors appear more successful on paper. Sources told the Journal that some investors in this round are coming in at the $13 billion valuation, while others are participating at $11 billion. The round is reportedly co-led by Spark Capital, Sands Capital, Altimeter Capital, and Wellington Management.

Founded in 2019, Baseten is riding what The Next Wave has called the "inference gold rush," where venture capitalists are pouring enormous sums into companies building the inference layer. Inference refers to what a model does after a user submits a prompt. Baseten promises to handle inference quickly while keeping costs under control by routing requests to the best-suited model for each task—particularly to capable, less expensive open-source alternatives.