9. 1 Introduction o About one-fifth of the output of U.s. firms is produced overseas o One-quarter of U.S. imports are between foreign affiliates and U.s. parent companles o Since the late 1980s. over half of u.s companies increased the number of countries in which they operate9-2 9.1 Introduction ⚫ About one-fifth of the output of U.S. firms is produced overseas. ⚫ One-quarter of U.S. imports are between foreign affiliates and U.S. parent companies. ⚫ Since the late 1980s, over half of U.S. companies increased the number of countries in which they operate