Six more investment banks invested in the BIDS Trading Service, bringing the total tally of investors to 12 as Wall Street banks and brokers scramble to back a variety of systems and exchanges in order to protect profits.

Bank of America, Bear Stearns, Credit Suisse, Deutsche Bank, JPMorgan and Knight Capital Group have invested in BIDS, which was founded by rivals Citigroup, Goldman Sachs, Lehman Brothers, Merrill Lynch, Morgan Stanley and UBS. BIDS is an electronic trading service for big block stock trades.