NEW YORK ( TheStreet) -- Two securities industry self-regulatory organizations issued a notice reminder municipal securities dealers of obligations to buyers. In a regulatory notice released Monday, the Financial Industry Regulatory Authority (FINRA) and the Municipal Securities Rulemaking Board (MSRB) reminded dealers of their obligation to provide customers buying bonds from them "all material information about the bond that is either known to them or publicly available through established industry sources," according to a FINRA press release Monday. The regulators also stressed that credit ratings are "only one factor to be considered, and dealers should not solely rely on credit ratings as a substitute for their own assessment of a bond." FINRA has been conducting sweeps of the municipal securities business, for example, looking at firms' procedures for disclosing material facts about bonds to investors. There have also been recent lawsuits in municipal securities, such as a class action case accusing more than 30 defendants, including General Electric ( GE - Get Report), AIG ( AIG - Get Report), and several large and regional banks, of anticompetitive practices. Morgan Stanley ( MS) recently settled that case for $4.95 million, in what an attorney representing the plaintiffs says is likely to be the first of many such deals. Underwriting activity is dominated by Bank of America ( BAC - Get Report), Citigroup ( C - Get Report), JPMorgan Chase ( JPM - Get Report)and Morgan Stanley together account for nearly half of all underwriting activity this year, according to Thomson Reuters data. Goldman Sachs ( GS - Get Report), however, has been trying to make inroads. -- Written by Dan Freed in New York.