ABSTRACT Research question: Ambush marketing occurs at all major sporting events, and Rule 40 of the Olympic Charter is designed to prevent ambush marketing tactics during the Olympic Games, restricting what content athletes can post on social media about non-Olympic sponsors. Utilizing ambush marketing as a framework to guide our examination of athletes’ adherence to Rule 40, the purpose of this study was to examine Olympic athletes’ social media posts from the 2016 Olympic Games to determine whether athletes violated Rule 40 and therefore engaged in ambush marketing. Research methods: Using content analysis, this study examined 100 randomly selected U.S. Olympic athletes’ social media posts on Instagram for a six-week time period before, during, and after the 2016 Rio Olympic Games. Frequencies, chi square, and independent samples t-tests were calculated with SPSS25. Results and findings: Significant differences in posting behaviors existed during the three time periods, and over 19% of all posts during the blackout period violated Rule 40, indicating a form of ambush marketing by the athletes. Additionally, athletes appeared to miss opportunities to highlight their personal sponsors and build their athlete brand after the Games. Implications: Athletes play a role in the Olympic ambush marketing network, whether intentionally or unintentionally, and Rule 40 enforcement issues were apparent, leading to questions about its feasibility. Athletes’ brand-building efforts should extend to the time period after the Olympic Games, as they have the ability to highlight sponsors in their posts to a greater degree during this timeframe.