We examine a new attenuated type of informed trading in which insiders exploit the private information obtained via their ties to rival firms’ insiders. We find that insiders earn abnormal profits by trading their firms’ stocks before the disclosure of rivals’ cyberattacks, particularly when their firms and rivals are exposed to higher cyber risk. Social networks formed through nonworkplace and nonboard ties are the main sources of trading profits. Insiders earn higher profits as rivals’ litigation risk and the information asymmetry of rivals and their firms increase, but they do not after the SEC’s 2011 guidance on cybersecurity risk disclosure.