The Consumer Financial Protection Bureau (CFPB) is reportedly looking into whether some of Zillow’s advertising revenues violate regulations against kickbacks, MarketWatch reports. The investigation centers around the Real Estate Settlement Procedures Act (RESPA). The CFPB is investigating Zillow’s “co-marketing” plan, which allows a real estate agent to share the cost of an ad on its website with a preferred lender. It can make those lenders or agents appear as they are receiving approval from each other or from Zillow, MarketWatch reports.