A new report by researchers at investment firm Keefe, Bruyette & Woods is warning that the real estate industry could be upended by a trio of lawsuits over agent commissions, including one involving Massachusetts’ main multiple listings service.

The National Association of Realtors’ 1.6 million-strong membership could fall to just 500,000, while the average commission rate per transaction could slump from 5.5 percent to just 3.5 percent and the usage of buyer agents could be cut in half, KBW analysists Ryan Tomasello, Thomas McJoynt-Griffith, Bose George, Jade Rahmani and Nikhil Vijay wrote. I

The report, aimed at investors in real estate brokerage companies like eXp World Holdings and Compass, predicts that CoStar Group is best positioned to benefit from the new structure while commission-driven brokerages like Anywhere Real Estate – parent to a diverse set of brokerage brands like Sotheby’s International and Century 21 – and Compass could suffer the most. Mortgage lenders and title companies would also be subject to significant disruption and be forced to find new ways of finding clients outside of the traditional agent referral method the report, first covered by Inman News, said.

“We believe disruption to the industry’s commission structure is all but guaranteed given the strength of the civil lawsuits arguments, changes that have already occurred to date, and the backstops provided by the [Federal Trade Commission and Department of Justice antitrust investigations]. While the timing and process through which this plays out are less certain, recent developments suggest that a banning of Cooperative Compensation is a very likely outcome,” the authors write.

Two lawsuits, Sitzer et al. v. National Association of Realtors et al. and Moehrl v. The National Association of Realtors, are seeking a combined $45 billion in damages from NAR and Keller Williams, RE/MAX, Anywhere and HomeServices of America on behalf of sellers who sold a home listed on MLS services in Missouri and Illinois, respectively, as early as 2015. The two suits claim that NAR and the four brokerage parent companies colluded to require sellers to pay the buyer’s agent’s commission and restrict competition among buyer and seller agents that might otherwise have driven down agent commission rates. The plaintiffs in both cases also want permanent rule changes that would undo NAR’s “participation rule” that has shaped standard real estate industry commission practices for decades.

The KBW analysts predict that NAR will likely seek a nationwide settlement in these cases to prevent “copycat” lawsuits across the country, but such a deal could dramatically increase the association’s membership dues by $1,000 or more per month, at a time when agent income is under severe pressure from a housing market being choked by high mortgage interest rates.

A third suit, Nosalek v. MLS Property Information Network, Inc. et al., seeks similar changes in Massachusetts-focused MLS PIN’s rules and internal practices at the same four national brokerage companies but only seeks damages awarded at trial.

The Sitzer case went to trial this week, but not before Anywhere and RE/MAX both agreed to settle it and the Moehrl case. MLS PIN agreed to settle the suit against it earlier this summer, but a judge’s ruling on that settlement has been delayed after federal antitrust prosecutors intervened, potentially seeking more stringent rule changes at the listings service. All three settlements effectively scrap current industry commission practices, and the Anywhere and RE/MAX settlements allow agents of those brands to drop NAR membership if they desire.

Federal antitrust prosecutors have separately been investigating NAR’s commission rules on similar grounds to the three commission lawsuits since the Trump administration.

Whether through the three lawsuits or follow-on actions by federal prosecutors and regulators, KBW said real estate agent compensation was likely to go one of two ways: a ban on commission-splitting and buyer-agent commission offerings published in an MLS – which would push buyers to compensate their agents directly – or allowing sellers the option of declining to offer buyer-agent compensation when listing their home on an MLS.

The latter is less disruptive, but the KBW report argues that press coverage a nationwide settlement in the commission lawsuits or federal antitrust efforts could put noticeable downward pressure on commissions.

And based on surveys of American consumer sentiment and practices in other countries where buyers compensate their agents directly, KBW wrote, buyer agent usage could drop sharply, while buyer agent commissions would come under significant pressure, potentially dragging down listing agents’ commission rates as well.