Mergers are moving quicker because federal regulators have changed some of the policies that deterred deals after the financial crisis, The Wall Street Journal reports.

Critics say that the mergers are not getting their due level of scrutiny and that some mergers could potentially hurt competition and make banks less available to those in rural areas.

Democratic presidential hopeful and Massachusetts Sen. Elizabeth Warren sent a letter to Fed Chairman Jerome Powell last week saying the “anemic scrutiny of applications for mergers and acquisitions raises concerns that [it] may oversee a wave of bank consolidation to the detriment of consumers and the financial system.”

Typically bank mergers are reviewed by both the Federal Reserve and Office of the Comptroller of the Currency. Those reviews can often take a long period of time for mergers that involve stocks. When those reviews take a long period of time, the market can potentially move and make the deal less beneficial for one of the companies, prompting them to back out.

Last week, BB&T and SunTrust Banks announced plans to merge in a $28.2 billion all-stock deal. If it happens, the merger will be the largest since the financial crisis and will make the combined entity the 6th largest bank in the United States.

Recently, the wait time in both agencies has dropped dramatically. At the beginning of 2018, the Fed was approving mergers in 3.8 months and the OCC 1.9 months, significantly less than the 5.6 months and 2.6 months respectively both took during the same time period in 2017. Both groups attribute streamlined internal steps as the reason for the faster approvals.