As a candidate in 2008, President Obama stated that he would increase antitrust enforcement, in contrast to President George W. Bush's administration, which he said produced "the weakest record of antitrust enforcement in the last half century." Statistics from the FTC and the U.S. Department of Justice (DOJ) indicate that the Obama administration has increased the frequency of enforcement actions. For example, the Bush administration, in its second term, issued second requests for additional information for approximately 3% of all transactions reported under the Hart-Scott-Rodino (HSR) Act, while the Obama administration issued second requests for approximately 4% of transactions. The Obama administration also revised the Merger Guidelines and the merger remedy guidelines (to be more receptive to behavioral remedies), as well as the HSR Form—all of which facilitated aggressive merger enforcement.

Cartel enforcement has seen little change since the end of the Bush administration, as the DOJ's Antitrust Division has continued to pursue criminal antitrust violations aggressively. In 2011, the Antitrust Division filed 90 criminal antitrust cases—the most since 1987. The Division has also collected more than $500 million in criminal fines in each of the last three years.

While cartel enforcement has continued unchanged, there has been a shift in nonmerger civil enforcement policy. The Antitrust Division repudiated the Bush administration's monopolization guidelines and has expressed a greater willingness to challenge unilateral conduct and exclusionary business arrangements. Although the stated policy has shifted, the Antitrust Division has only brought one monopolization case during the Obama administration.