When number one pharmacy chain Walgreens announced its deal to purchase number three chain Rite Aid, many antitrust observers warned the deal would face tough regulatory scrutiny. New revelations about the deal now show that the antitrust issues could be not only challenging but expensive for the company.

Walgreens put up $9.4 billion for Rite Aid, but there is still uncertainty as to whether antitrust authorities will allow the deal, according to the New York Times. Rite Aid insisted on provisions in the deal that require Walgreens to dispose of certain stores and assets, in anticipation of antitrust concerns.

Walgreens won three conditions that limit their commitment to divestiture. First, they are not required to sell off more than 1,000 of the companies’ combined stores. Second, Walgreens is not disclosing which stores they may close or when the closures will occur – a troubling premise to some analysts, who say that non-disclosure of such information that is material to shareholders may be a violation of securities law. The third condition is not completely clear, but the agreement appears to suggest that Walgreens does not have to divest of more than $100 million worth of assets that do not generate revenue.

The deal also calls for Walgreens to make a $325 million payment if antitrust issues end up scuttling the merger, which can go up to $625 million if antitrust issues kill the deal 8 months after regulatory approval is pending.

During the first 8 months following regulatory approval proceedings, Walgreens is barred from making any significant acquisitions. But prior to the Rite Aid deal, Walgreens was actively pursuing other chains, including the popular Duane Read drug store chain, as well as USA Drugs and Kerr Drug stores.

Investors believed that the conditions in the Rite Aid deal were favorable to Walgreens, but the details now have some observers concerned. Ultimately, the decision of antitrust regulators may prove costly to Walgreens.