Is the extraction of private benefits by the firm’s controllers only an issue for minority or non-controlling shareholders? Korea’s treatment of such conduct (often called “tunneling”) provides useful insights to this question. Tunneling by controlling shareholders, which has traditionally been the concern of corporate governance law and policy in the U.S., is further subject to scrutiny under competition law (Undue Support Clause) in Korea. This Article discusses a real world example of an intersection between competition law and corporate governance policy from a comparative perspective. The history of the Undue Support Clause challenges the common perception that a corporate governance malady has nothing to do with competition law (or vice versa). Although this is not a complete survey of all the intricacies that can arise when competition and corporate governance intersect with one another, Korea’s experience with the Undue Support Clause provides an invaluable opportunity to reevaluate the relationship between the two policies and draw valuable insights for other jurisdictions, including the U.S., that tend to turn a blind eye towards harm inflicted outside of the firm by tunneling.