When Morgan Stanley released its third-quarter report in Novem­ber, it chose to make an unusual disclosure to its investors: The bank had received a letter from Gibbs & Bruns.

The partners at the Houston-based boutique say they did not expect to find one of their letters cited by the company as a material event. Yet they also say the disclosure was justified given the circumstances. A similar letter had, after all, ultimately resulted in Bank of America Corp. agreeing to pay $8.5 billion to investors in troubled mortgage-backed securities issued by Countrywide Financial Corp.