(Adds details of proposal, background, quotes)
By Katanga Johnson and John McCrank
WASHINGTON, Feb 14 (Reuters) - The U.S. Securities and Exchange Commission (SEC) proposed on Friday to add more stock price information to public market data feeds and allow other firms to compete against the exchanges in running them.
The data is related to systems called securities information processors, or SIPs, which consolidate stock orders and last sales prices from the 13 U.S. stock exchanges. Regulators use the information to determine the best market prices, which brokers must give their clients when executing trades.
The data feeds show current best prices and last trades for stocks.
The SEC proposal seeks to add so-called "depth of book" information to the SIPs that includes prices of stocks available in the pubic market that are below the best bid and above the best offer available.
Most exchanges offer depth of book data as a proprietary, fee-based service. The agency measure would give many market participants a fuller view into buying and selling interest in the market.
Brokers and trading firms have long complained that the exchanges are conflicted in their role as SIP providers -- and have little incentive to improve them -- because they sell products that compete against the public feeds.
Friday's proposal, which is subject to public consultation, could help ease the conflict of interest. It could also pressure the market data revenues of exchanges, such as Intercontinental Exchange Inc's New York Stock Exchange, and Nasdaq Inc, as the SIP could become more competitive with the exchanges' proprietary market data feeds.
In a statement, SEC Chairman Jay Clayton said the measure was "designed to improve data quality and data access for all market participants."
"Both the content and the technologies used to collect, consolidate and disseminate market data have lagged meaningfully behind proprietary data products and systems offered by the exchanges," he said.
The SEC on Jan. 8 proposed a series of governance changes to the SIPs aimed at improving transparency and addressing inefficiencies in the collection and dissemination of the data.
The proposal, currently open to a public comment period, directs the exchanges to create a new governance plan that would form a single plan for the three public data feeds, reduce the influence of large exchange groups in decision-making around the data, and give non-exchange participants a bigger say in SIP decisions. (Reporting by Katanga Johnson in Washington and John McCrank in New York; Editing by Chris Reese and Tom Brown)