It may be Christine Varney’s October surprise.

In Varney’s first 18 months on the job as head of the U.S. Department of Justice’s Antitrust Division, agency lawyers have litigated just one civil case in federal court, against Dean Foods Co. That is, until October. In the space of two weeks, DOJ filed two high-profile antitrust suits, one against the major credit-card companies, the other targeting Blue Cross Blue Shield of Michigan.