FACTBOX-S&P 500 companies that rely most on revenue from Mexico

May 31 (Reuters) - U.S. stocks dropped on Friday after President Donald Trump's threat to impose a tariff on all goods from Mexico until the flow of illegal immigrants across the southern border ceases. Trump plans tariffs to start at 5% on June 10 and increase monthly up to 25% on Oct. 1 unless Mexico takes immediate action. The S&P 500 fell 1.2% in afternoon trading. Here are the companies in the benchmark index that depend most on revenue from Mexico, according to FactSet*: COMPANY NAME RIC MEXICO SUB-INDUSTRY REVENUE EXPOSURE (PCT) Kansas City 47.5% Railroads Southern Allegion 12.2% Building products Union Pacific 10.9% Railroads Sempra Energy 10.8% Multi-utilities BorgWarner 9.3% Auto parts & equipment HanesBrands 8.1% Apparel accessories & luxury goods American Tower 6.1% Specialized REITs PepsiCo 6.0% Soft drinks LyondellBasell 5.9% Commodity chemicals Arista 5.4% Communications Networks equipment * FactSet said it gathers data from annual SEC filings when provided or, when not provided, generates data from a FactSet proprietary algorithm (Reporting by Lewis Krauskopf; Editing by Cynthia Osterman)