; and (B) is not affiliated with the person through direct or indirect ownership or control. (b) Prohibitions No person with more than $20,000,000,000 (as adjusted each year on January 1 by an amount equal to the percentage increase, if any, in the Consumer Price Index, as determined by the Department of Labor or its successor) in digital advertising revenue during the previous calendar year may, after the effective date— (1) own a digital advertising exchange if the person— (A) owns a sell-side brokerage or a buy-side brokerage; or (B) is a seller of digital advertising space; (2) own a sell-side brokerage if the person owns a buy-side brokerage; or (3) own a buy-side brokerage or a sell-side brokerage if the person is a buyer or seller of digital advertising space. (c) Requirements On and after the effective date, any person with more than $5,000,000,000 (as adjusted each year on January 1 by an amount equal to the percentage increase, if any, in the Consumer Price Index, as determined by the Department of Labor or its successor) in digital advertising revenue during the previous calendar year shall be subject to the following requirements: (1) Best interest duty A buy-side brokerage or sell-side brokerage— (A) shall, in the course of providing services as a brokerage, use reasonable diligence, care, and skill to act in the best interests of the brokerage customers