European companies aren't alone in their Brexit pain. Pfizer Inc., the U.S.-based drug behemoth, says its costs for dealing with the upcoming split will reach $100 million.

The U.K.'s looming rupture with the European Union (EU) threatens to slow goods at borders that are now wide open and force companies to duplicate regulatory efforts. Pfizer said in an email that its costs stem from transferring product testing and licenses to other countries, changing clinical-trial management procedures, and other preventive measures.

The company is working “to meet EU legal requirements after the U.K. is no longer a member state, especially in the regulatory, manufacturing, and supply-chain areas,” according to a filing last month where it cited the cost estimate.