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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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Commodity Futures Trading Commission (CFTC) Acting Chairman Caroline Pham, currently the only CFTC Commissioner of the five-member commission, announced on Dec. 4, 2025, that spot trading in cryptocurrency products will…

Continue Reading CFTC Opens Door to Spot Crypto Trading on Regulated Exchanges

On Sept. 8, 2025, the Nasdaq Stock Market filed a proposed rule change with the U.S. Securities and Exchange Commission to enable the trading of tokenized equity securities and exchange-traded products on its platform. The proposal, published for public comment, represents a significant step toward integrating blockchain-based assets into the existing U.S. equities market infrastructure.…

Continue Reading Nasdaq Proposes Rule Changes to Enable Trading of Tokenized Securities

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