The startup Baseten is close to closing a new round of 1.5 billion dollars, at a valuation of 13 billion dollars - just five months after raising 300 million at a 5-billion valuation. That's a jump in value of 160 percent in under six months. When a company is revalued threefold in less than a year, the question isn't whether it's growing, but who decided it's worth that much - and why right now.

Baseten works in what the industry calls the "inference gold rush" - the computing work that happens after a user sends a query to some AI model. The company, founded in 2019, makes money by routing those queries to the most cost-effective models, including open-source solutions, and in that way keeps costs under control. The business is real; what's questionable is the pace at which investors are throwing money at it.

The detail that reveals the most is the structure of the deal: some investors are coming in at a valuation of 13 billion, others at 11 billion for the same company in the same round. When they can't even agree on what it's worth, that says that even the big funds themselves - among them Spark Capital, Altimeter and Wellington - aren't sure of the number, but are afraid to miss out. That's the logic of a bubble: you don't buy because you know it's worth it, but because everyone around you is buying.