A British retail regulator has warned sellers against price fixing online. The CMA reportedly found evidence online that suggested that businesses on marketplace sites, such as Amazon, were agreeing not to undercut each other's prices. This sparked a wider investigation into the issue and has prompted the authority to write up a guide, ready to be supplied to online retailers. The guide has been developed in order to remind retailers of the legal consequences of being found to be discussing pricing with competition. Recently, the CMA has fined a poster company £160,000 for breaking price-fixing laws.