Corporate-bond brokers may face a squeeze on profits asregulators start publishing prices for almost $1 trillion ofprivately sold debt, if the past is any guide.

The Financial Industry Regulatory Authority, seeking to “fostermore competitive pricing,” plans to start disseminating tradinglevels for securities issued under a rule known as 144a on its11-year-old Trace system within the next year. That means thenotes, sold only to institutional investors, will face the sameprice transparency as publicly registered corporate bonds for whichbuyers demand half a percentage point less in yield spreads.Brokers typically are paid larger fees from higher-yieldingdebt.

Firms from Knight Capital Group Inc. to Gleacher & Co. andPierpont Securities LLC sold or shuttered credit units this year ascorporate-bond trading volumes fell to the lowest proportion of themarket on record and smaller price swings shrink potential profitmargins. In the 90 days after Trace started disseminating prices ofjunk bonds, trading in the securities dropped 41 percent, accordingto Massachusetts Institute of Technology and Harvard Universityresearchers.