A nonprofit antitrust advocacy group is already opposing CVS Health’s (NYSE:CVS) potential purchase of Oak Street Health (NYSE:OSH) before it’s even announced after a report about a possible transaction on Monday.

The American Economic Liberties Project said the Federal Trade Commission should immediately seek to block a potential transaction, according to a statement on its website.

The opposition comes after a WSJ report late Monday that CVS Health (CVS) is close to striking a deal to acquire the Oak Street (OSH) for more than $10.5 billion. A potential acquisition would value Oak Street (OSH) at $39/share.

“This deal will be especially disastrous for seniors, who will have little choice but to rely on CVS’s notoriously poor customer service model combined with Oak Street’s physician practices, which have reportedly been staffed without any doctor on site,” Sara Sirota, policy analyst at the American Economic Liberties Project,  said in the statement. “TheFederal Trade Commission should immediately look to block it.”

Oak Street Health on Tuesday said that as a matter of policy, it would not comment on “unusual market activity” that has sent the shares of the primary care provider 30% higher.

CVS Health (CVS) is set to report Q4 results before the open on Wednesday.