We present evidence of a persistent violation of the law of one price in the U.S. stock market. Using a hand collected dataset which corrects for the data errors in SDC, we find that the value of the parent’s ownership in the subsidiary can exceed the parent firm’s total market value consistent with prior literature. Contrary to what efficient capital markets would suggest, this price aberration is persistent, and we show that it is possible to profitably trade by taking advantage of the price discrepancy.