Amazon is contacting third-party sellers to warn them of how impending action by Congress could impact them.

Congress seems determined to tackle issues with Big Tech, including what it perceives as antitrust violations and monopolistic behavior. Amazon is one of the companies Congress has its sights set on, and this is already a concern for the e-commerce giant.

According to CNBC, the company has begun contacting some of its third-party sellers, one of its biggest growth markets, to inform them of how they may be impacted.

“We’re reaching out to a small group of our sellers to make them aware of a package of legislative proposals, currently in Congress, that is aimed at regulating Amazon and other large technology companies,” states the email, send by CNBC. “It is early in the process and the bills are subject to change, but we are concerned that they could potentially have significant negative effects on small and medium-sized businesses like yours that sell in our store.”

As Amazon points out, there is much that could change before the antitrust bills make it into law. Nonetheless, the threat of the bills is already causing major concern.