U.S. companies trying to avoid running afoul of the recent sanctions against Russia face a monumental challenge: Figuring out which companies are owned by those blacklisted. Some of the people and entities on the new lists of sanctions, part of the U.S. government’s effort to pressure Russia over the conflict in Ukraine, have extensive connections to other companies in countries throughout the world. That poses hurdles for American companies, which are restricted in doing business with some companies owned by those that are blacklisted. The U.S. has put 50 entities and 57 individuals on the new Russia and Ukraine sanctions lists since March, according to the U.S. Treasury Department. But those 107 parties hold ownership stakes or potentially exercise control of thousands of other companies around the globe, sometimes indirectly, according to data compiled by Dow Jones Risk & Compliance.