UNITED PARCEL SERVICE, INC. v. POSTAL REGULATORY COMMISSION - Leagle TATEL, Circuit Judge. The U.S. Postal Service holds congressionally authorized monopoly power over the market for some of its products, like first-class mail delivery, but for other products, like parcel post, it competes with private companies. To promote fair competition, Congress tasked the Postal Regulatory Commission with ensuring that the Postal Service sets competitive products' prices high enough to cover all "costs attributable to [those] product through reliably identified causal relationships." 39 U.S.C. § 3631(b); see also id. § 3633(a)(2). In two 2016 orders, the Commission directed the Postal Service to include among the "costs attributable" to competitive products those costs that would disappear were the Postal Service to stop offering those products for sale. United Parcel Service, Inc., which competes with the Postal Service, petitions for review of both orders, arguing that the cost attribution methodology the Commission embraced is both inconsistent with the statute that gives the Commission its regulatory authority and arbitrary and capricious. For the reasons that follow, we deny the petitions.