AI inference company Baseten is close to finalizing a stunning $1.5 billion funding round at a $13 billion valuation, the WSJ reports. Just five months ago, the startup announced that it had raised a $300 million Series E at a $5 billion valuation. And that round was just nine months after raising a $150 million Series D.

If finalized, this latest round would represent a 160% increase in valuation in less than half a year. However, the WSJ reports that this is a split-priced round, a tactic startups are using to boost their headline valuation and make lead investors look good on paper. Some investors in this latest funding round are reportedly coming in at a $13 billion valuation, while others at $11 billion, sources told the Journal. This deal is said to be co-led by Spark Capital, Sands Capital, Altimeter Capital, and Wellington Management. 

Launched in 2019, Baseten is a startup benefiting from what The Next Wave hailed the “inference gold rush,” in which VCs are pouring enormous amounts of money into companies building the inference layer. Inference is what the model does after a user submits a prompt. Baseten promises to handle inference quickly while controlling costs by routing requests to the best-for-task model, especially to competent, less-expensive open source alternatives.