Hightouch, an ad tech startup recently valued at $2.75 billion, has offered to buy LiveRamp's identity business from ad holding group Publicis for $800 million–$1.2 billion in cash and stock, according to a letter sent to Publicis' board last week and obtained by Axios. Why it matters: A fast-growing ad tech startup is trying to convince Publicis to sell off a significant part of LiveRamp before the ink is even dry on its acquisition.Publicis last month announced a $2.2 billion all-cash deal to take LiveRamp private, marking one of the biggest ad tech acquisition agreements since Publicis bought Epsilon in 2019.The big picture: Hightouch's proposal reflects concerns across the advertising industry about Publicis owning infrastructure that many agencies, brands and technology providers rely on.Almost immediately after Publicis announced the LiveRamp deal, rival agencies and some analysts questioned whether advertisers would start looking more aggressively for alternatives.Publicis did not immediately respond to a request for comment.State of play: Hightouch is interested in LiveRamp's identity and data onboarding businesses such as RampID and LiveRamp Connect.The offer amount is based on publicly available information, the letter said, adding Hightouch's final offer may be subject to adjustment after it completes due diligence on a possible deal. The transaction would be financed through a combination of cash, debt financing and Hightouch equity, according to the letter. The company said it is prepared to move quickly through due diligence and complete a transaction if Publicis is interested.Zoom out: Founded in 2019, Hightouch has quickly become one of the fastest-growing agentic marketing startups in the U.S.In April, the company raised a $150 million Series D, led by Goldman Sachs and Bain Capital Ventures, at a $2.75 billion valuation.The firm helps brands build customer data profiles in conjunction with their cloud data providers, such as Snowflake or Databricks. LiveRamp's assets could help it scale to a much wider customer base. What to watch: Hightouch says it will withdraw its proposal if it doesn't receive a response from Publicis by June 26.