The capture theory of regulation concludes that regulatory agencies tend to be captured by the firms they are regulating. This paper tests the capture theory in the recent environment of nuanced agency regulation by the administrative state, focusing on the U.S. oil refining industry. Regulation has tended to narrow refiners’ margins, which harms nonintegrated oil refiners more than vertically integrated. Providing evidence of regulatory capture, complementary analysis of stock returns shows that regulations have benefited the stocks of vertically integrated firms. The narrowing of the margins is primarily due to rising input costs.