Also, a commonly used abbreviation for the Investment Dealers Association, a self-regulatory organization of financial firms in Canada. All brokerage houses are covered by the various provincial Securities Acts, but the IDA provides additional regulations that member firms must follow, which are generally more stringent than the law. Among them is a capitalization requirement for member firms, which is to the advantage particularly of smaller, independent members, since the consumer then knows that any IDA member firm they deal with, large or small, isn't likely to go out of business any time soon.