San Francisco adtech firm Gravity closed a $30.5 million Series A co-led by Lightspeed and Committed Capital, taking total funding to $38.5 million. It runs demand-side tools for brands, supply-side tools for AI developers, and an exchange between them, placing text ads in ChatGPT and other assistants for clients such as Best Buy, Target, Vercel, and MongoDB. Gravity is also testing agent-to-agent ads that feed catalogues to shopping bots humans never see. WPP Media projects $100 billion in generative AI search ads by 2030. Caveat: Google and OpenAI are building rival ad stacks, so an independent exchange must still prove inventory and measurement hold.