Despite marked parallels in the language of their antitrust laws and the increasing use of economic expertise in developing agency positions, the United States and the European Union exhibit strong continuing differences in competition policy. This is especially true in policy towards what is called "the new economy" or "dynamically competitive industries." This article first explicates a recurring pattern that typifies much of the new economy and identifies intellectual property interacting with network effects as the central dynamic. In some critical industries, this interaction generates a uniquely powerful, but also uniquely vulnerable, competitive situation. Transatlantic policy differences towards dynamically competitive industries are documented, and the roots of those differences are explored in three dimensions: institutions; ideology and doctrine; and economic nationalism.