Wall Street’s chief regulator and the nation’s antitrust watchdog agreed to a formal partnership that could result in greater scrutiny of the fees charged by stock exchanges for crucial market data.

The Securities and Exchange Commission and the US Justice Department unveiled the memorandum of understanding Monday at an event in Washington. The SEC has recently clashed with exchanges over the fees levied for their most robust data products. Now, the move to involve the Justice Department, with its authority over competitive markets, will beef up the SEC’s ability to examine whether exchanges abuse their quasi-monopoly status to overcharge for data, as a number of big banks, brokerages and trading firms allege.