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William Mack

William B. Mack is a co-chair of the Financial Regulatory and Compliance Practice. He is experienced in advising companies on regulatory and compliance matters relating to the Securities and Exchange Commission regulations, the Exchange Act, Anti-Money Laundering laws and Financial Industry Regulatory Authority (FINRA) rules.

William’s practice involves all aspects of broker-dealer regulation, including Self-Regulatory Organization (SRO) membership, supervision, employment, research, soft dollar arrangements, chaperoning of foreign broker-dealers, social media, use of foreign finders, anti-money laundering rules, alternative trading systems (ATS), exchanges, and market making issues. He also provides regulatory guidance to investment banking clients in connection with securities offerings and related trading issues.

 

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On April 7, 2025, U.S. Deputy Attorney General Todd Blanche issued a memorandum titled “Ending Regulation by Prosecution” (Blanche Memo), outlining a new Department of Justice approach to digital asset enforcement.
Continue Reading Justice Department Issues Memorandum Realigning DOJ’s Crypto Enforcement Efforts

On Nov. 26, 2024, in what has been deemed a win for open-source technology, the U.S. Court of Appeals for the Fifth Circuit reversed the district court’s ruling in Van…

Continue Reading Fifth Circuit Rejects OFAC Sanction of Tornado Cash Crypto Code

U.S. Sen. Cynthia Lummis (R-WY) and Reps. Wiley Nickel (D-NC) and Mike Flood (R-NE) are working to overturn a controversial Securities and Exchange Commission (SEC) staff accounting bulletin, SAB 121…

Continue Reading Lawmakers Introduce Resolution to Nullify SEC’s Crypto Accounting Bulletin
  1. Continued Robust Litigation and Enforcement Actions by Federal and State Regulators and Enforcement Authorities – We will likely see a similar level of anti-fraud prosecutions by the Department of Justice
… Continue Reading 5 Trends to Watch: 2024 Blockchain

On Sept. 18, 2023, the New York State Department of Financial Services (NYDFS) issued a press release announcing updates to its ongoing oversight of the digital asset space, including (1)…

Continue Reading NYDFS Updates Guidance on Virtual Coin-Listing/Delisting Frameworks and the Greenlist

On Aug. 29, 2023, the U.S. Court of Appeals for the District of Columbia Circuit (Court) vacated the U.S. Securities and Exchange Commission (Commission)’s denial of Grayscale Investments, LLC (Grayscale)’s…

Continue Reading SEC Denial of Proposed Bitcoin Exchange-Traded Product Arbitrary and Capricious: DC Circuit

On Aug. 28, 2023, the Securities and Exchange Commission (Commission) charged Impact Theory, LLC, a media and entertainment company, with violating Sections 5(a) and 5(c) of the Securities Act of…

Continue Reading SEC Charges Media and Entertainment Co. for Unregistered Offering of NFTs

On May 17, 2023, Prometheum Ember Capital LLC (Prometheum Ember Capital), a subsidiary of Prometheum Inc., received approval from the Financial Industry Regulatory Authority (FINRA) to…

Continue Reading FINRA Approves Prometheum Ember Capital LLC to Operate as Special Purpose Broker-Dealer for Digital Assets

On Dec. 14, 2022, the SEC announced charges against eight social media influencers in a $100 million securities fraud scheme in which they allegedly used social media platforms to tout…

Continue Reading 8 Influencers Charged in $100 Million Securities Fraud Scheme