June 30 (Bloomberg) -- Investors will have access to public price information in the $1.5 trillion market for privately-sold corporate bonds beginning today.

The Financial Industry Regulatory Authority will start disseminating prices on company bonds issued under Rule-144a, the latest step in the agency’s effort to make over-the-counter debt markets more transparent. The move represents the biggest expansion of Finra’s corporate-bond price disclosure on its Trade Reporting and Compliance Engine since 2006.

“People go to the market with numbers in hand and use them in negotiations,” said Steven Joachim, an executive vice president at Finra. “We’ve found that as we’ve disseminated prices, it influences trading in many ways.”