There is no way to clearly identify a Brokerage firm as an IRB versus an investment banking firm. The Broker/Analyst Translation files only provide names, without further specifications. Broker/Translation table has not been provided by Thomson since 2007.
IBES once talked about providing a list, but this never progressed.
Under U .S. law, all registered broker-dealer firms must file audited annual financial statements with the Securities and Exchange Commission (SEC) in x-17a-5 filings. These filings contain information on broker-dealer firms' principal sources of revenue, broken down into revenue from investment banking, brokerage commissions and all other businesses (such as asset management and proprietary trading). These filings can be accessed from Thomson Financial Global Access database and the SEC's public reading room in Washington, DC. The electronic availability of x-17a-5 filings is very limited prior to 1994, the year the SEC first mandated electronic form filing.