New U.K. Prime Minister Theresa May says "Brexit means Brexit," but many companies are struggling to figure out what the country's departure from the European Union will bring for them. Outside advisers are eager to lend a hand.

Banks like Citigroup Inc. and  Nomura Holdings Inc. have set up internal Brexit teams and Goldman Sachs Group Inc. has hired Jose Manuel Barroso, former president of the European Commission, to guide it through the thickets in Brussels. 

Outside the financial services industry, responses have ranged more widely. International telecoms giant Vodafone Group Plc has not set up a Brexit squad despite warning that it might have to move its headquarters away from London, while U.K.-focused discount retailer Poundland Group Plc — confronted with a rise in prices of imported goods it sells because of a plunging pound — has created such a panel, executives said.