Briefly

The Securities and Exchange Commission plans to subpoena at least five of the seven New York Stock Exchange market-making firms, expanding a probe of alleged trading violations, sources said Thursday.

The firms, which the NYSE said this month broke rules intended to provide investors the best prices, may get subpoenas within days, the people said.

The firms include LaBranche & Co., Goldman Sachs Group Inc.’s Spear, Leeds & Kellogg, Van der Moolen Holding, Bear Stearns Cos.’ Bear Wagner Specialists and FleetBoston Financial Corp.’s Fleet Specialists.