On November 3, 2014, the SEC instituted settled administrative proceedings against National Securities Corp. According to the SEC: "These proceedings involve the sale of non-investment grade or 'junk' bonds issued by the Puerto Rico by National Securities, a registered broker-dealer and municipal securities dealer, to a customer in an amount below the minimum denomination of the issue."

The Commission stated: "The Commission sanctioned 13 firms for violating a rule primarily designed to protect retail investors in the municipal securities market. Municipal issuers often set high minimum denomination amounts for so-called "junk bonds" that have a higher default risk, which may make the investments inappropriate for retail investors. Because retail investors tend to purchase securities in smaller amounts, this minimum-denomination standard helps ensure that dealer firms sell high-risk securities only to investors who are capable of making sizeable investments and are more prepared to bear the higher risk. In its surveillance of trading in the municipal bond market, the SEC Enforcement Division's Municipal Securities and Public Pensions Unit detected improper sales below a $100,000 minimum denomination set in a $3.5 billion offering of junk bonds by the Commonwealth of Puerto Rico in 2014. The SEC's subsequent investigation identified a total of 66 occasions when dealer firms sold the Puerto Rico bonds to investors in amounts below $100,000. The agency instituted administrative proceedings against the firms behind those improper sales. The enforcement actions are the SEC's first under Municipal Securities Rulemaking Board (MSRB) Rule G-15(f), which establishes the minimum denomination requirement. National Securities Corp. agreed to settle the SEC's charges and pay a penalty. The Commission's order against National Securities Corp. finds that, in addition to violating MSRB Rule G-15(f) by executing sales below the minimum denomination, it violated Section 15B(c)(1) of the Securities Exchange Act of 1934, which prohibits violations of any MSRB rule. Without admitting or denying the findings, National Securities Corp. agreed to be censured and to review its policies and procedures and to make any changes necessary to ensure proper compliance with MSRB Rule G-15(f)."