The antitrust complaint is expected to focus on how Amazon’s pricing policies, already the subject of a suit by California’s attorney general, Prime, and allegations the company illegally ties merchant access to its marketplace to the use of its logistics service, the people said, speaking on the condition of anonymity to discuss a pending complaint. Prime membership has been a key differentiator for Amazon, helping it convert occasional shoppers into loyal devotees who make the company their default choice when shopping online.

Politico first reported the news on Friday.

The antitrust and consumer protection agency has had Amazon in its sights for more than four years. The FTC during the Trump administration opened a probe into potential anticompetitive conduct related to several aspects of Amazon’s business, including its marketplace where both the company and third-party merchants sell goods and the Prime subscription service. Under Khan, the agency refined the probe and opened new investigations into the tech company. In August, company executives met with Khan and the FTC’s two other commissioners to discuss the potential suit, though no settlement was offered.

The agency sued Amazon in May in two separate cases for failing to delete data about children collected by its Alexa speakers and illegally spying on users of its Ring doorbells and cameras. Amazon said it disagreed with the FTC’s allegations but agreed to pay $30.8 million to resolve the suits.

A month later, the agency filed another suit against the company, alleging that it duped consumers into signing up for the Prime subscription service and then deliberately made it difficult to cancel. The FTC recently amended its complaint to add three Amazon executives as defendants in the case, arguing the trio ignored pleas by employees to stop using techniques “to mislead or trick users” into “signing up for a recurring bill.” The company is contesting the allegations in that case.