Free-ranging wild pig (Sus scrofa) populations may cause widespread environmental damage and transmit diseases at the wildlife-livestock interface. For example, African swine fever (ASF) is a highly contagious viral disease of pigs capable of causing catastrophic economic losses. Prevention and preparedness for ASF require understanding wild and domestic pig movements and distribution. We characterized a “grey” swine market and described the risks it poses, contributing to the threats associated with wild pig populations. We monitored www.kijiji.ca, a Canadian internet classified advertising service, for sales of domestic wild boar, pot-bellied pigs, other breeds, and their hybrids across Canada from 28 April to 30 June 2021. Data collected included seller-defined breed, age, sex, number for sale, sexual intactness, presence of identifying tags or tattoos, and the date and location of listings. Advertisement locations were mapped and compared with existing wild pig distributions, identifying areas new populations might be established, and existing populations supplemented or genetically diversified. We identified 151 advertisements on Kijiji: 34% (n=52/151) from Ontario, 29% (n=44/151) from Alberta, 41% (n=62/151) from existing wild pig populations, and 59% (n=89/151) from areas where wild pigs have not yet been identified. We propose requiring the use of individual animal identifiers (tags/tattoos), genetic analysis, and mandatory reporting for all pig sales in Canada to aid in ASF preparedness and to increase regulation and enforcement of the online swine market.