Existing literature in bundling and competition established analytically the competitive advantage of bundling: that economies of aggregation can be used to discourage or foreclose entry. In our application, we conduct an empirical study to verify these theoretical competitive implications. We study transactions at two online vendors who both provide various bundling options to sell the same popular electronic device with a mixed bundling strategy: the device alone, as well as bundled with other complementary goods of minor value, both informational and physical. We used purchase data at both vendors during a common period, and found evidence of competition in the bundles but not the stand-alone case.