The settlement would end the Justice Department’s court-ordered mediation with McKinsey over its work for three bankrupt companies: Alpha Natural Resources, Westmoreland Coal and SunEdison. The agreement requires approval by bankruptcy judges in Richmond, Va.; Houston; and New York City.

McKinsey was also in mediation with Mr. Alix, who formed a small investment company that bought some of the companies’ unsecured debt as part of his efforts to expose what he has called improper conduct by McKinsey. The mediation was an unusual joint step ordered by three bankruptcy court judges intended to head off a full trial.

Mr. Alix said Tuesday that he and McKinsey had failed to reach an agreement and that he would press his claims in court, including that McKinsey improperly profited from stakes in bankrupt client companies held by its investment division, MIO Partners.

“This is not really the last stop on the train,” he said of the mediated settlement with the Justice Department. “McKinsey today is not in compliance with the United States bankruptcy code in any of these cases, and they need to be held accountable.”

Under the settlement, the department said it would no longer investigate McKinsey’s disclosures in the 14 bankruptcies the firm has advised since it began advising insolvent clients in 2001. But it reserved the right to file new complaints if it gets new information that McKinsey has committed fraud or is not “disinterested,” as required, in one or more of those cases.