William B. Mack, Business Attorney in New York
Over 22 years of legal practice · focused on Business, General, and Government
ShareholderatGreenberg Traurig, LLP
New, NY
Practicing business in New York since 2004.
- 22+
- Years practicing
- 1
- Bar admission
Practices in
Are you William B. Mack?
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Quick answer
William B. Mack is a shareholder based in New York, NY. The practice focuses on Business, General, and Government. William has over 22 years of legal experience. Currently practicing at Greenberg Traurig, LLP.
- Based in
- New York, NY
- Experience
- over 22 years
- Known for
- Business · General · Government
- Handles Business, General, and Government matters from New York, NY.
- Over 22 years of practice as a licensed attorney.
About William B. Mack: William B. Mack is a shareholder based in New York, NY. The practice focuses on Business, General, and Government. William has over 22 years of legal experience. Currently practicing at Greenberg Traurig, LLP.
Areas of practice
Practice areas handled by William B. Mack
William concentrates on business, general, and government. Each area below outlines the kind of case William handles, typical outcomes to expect, and how the intake process starts.
Business
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General
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Government
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Business cases in New York
William takes business matters in New York. Typical engagements include intake calls to scope the issue, review of any records or filings you already have, and a written strategy memo before William agrees to represent you.
General cases in New York
William takes general matters in New York. Typical engagements include intake calls to scope the issue, review of any records or filings you already have, and a written strategy memo before William agrees to represent you.
Government cases in New York
William takes government matters in New York. Typical engagements include intake calls to scope the issue, review of any records or filings you already have, and a written strategy memo before William agrees to represent you.
Biography
About William B. Mack — Over 22 years of New York business experience
William B. Mack is a shareholder based in New York, NY. The practice focuses on Business, General, and Government. William has over 22 years of legal experience. Currently practicing at Greenberg Traurig, LLP.
William B. Mack is a co-chair of the Financial Regulatory & 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.
William advises firms in the FINRA new membership (NMA) and the continuing membership (CMA) processes. William assists firms to develop or amend their written supervisory procedures and compliance manuals.
William routinely represents clients who are negotiating placement agent agreements, foreign finders agreements, clearing agreements, agreements with registered representatives and expense-sharing agreements.
William assists broker-dealers and their associated persons to respond to regulatory examinations and inquiries and provides effective representation in a range of enforcement proceedings with the SEC, FINRA, NYSE, state and foreign regulatory authorities. He regularly prepares and defends witnesses in FINRA on-the-record interviews and SEC testimony. Enforcement matters have involved issues including market manipulation, supervision, customer defalcations, insider trading, anti-money laundering, distribution of unregistered securities, direct market access, market making, soft dollar arrangements, cross border trading, electronic intrusion and customer impersonation, sales practices, supervision, private placements, ETFs, indexes, and other securities products.
William regularly addresses questions with respect to what activities require or are exempt from broker-dealer registration. William assists firms in obtaining guidance, interpretive letters, and no-action relief from FINRA and the SEC with respect to novel securities issues and the creation of new products and services. William also advises clients on cryptocurrency, tokenization, NFTs, DeFi structures, and digital asset exchanges and trading.
Prior to joining the firm, William was a Principal Counsel for Enforcement at FINRA. Before FINRA, he was the Director of the Executive Secretariat in the Office of the U.S. Trade Representative. William also served as a Deputy Associate Counsel at the White House, advising primarily on appointments and investigations. Before the White House, he practiced at large firms in New York. William clerked for Judge Robert L. Carter in the Southern District of New York.
Judicial Clerkships
•Hon. Robert L. Carter, U.S. District Court for the Southern District of New York
Recognition & Leadership
Awards & Accolades
•Listed, The Legal 500 United States,
•Finance - Financial Services Regulation, 'Recommended Lawyer,' 2023-2024
•Finance - Fintech, 'Recommended Lawyer,' 2024
•Team Member, City & State, 'Top 50 NYC Lobbyists,' 2021
•Listed, The Legal 500 United States, Fintech, 2020
•Team Member, Best Lawyers in America 'Top Listed - Government Relations,' 2018
•Recipient, University at Albany Alumni Association, 'Excellence in Public Service Award,' 2018
•Listed, City & State’s 'New York City 40 under 40 Rising Stars,' 2015
William's approach to business cases
William B. Mack is a co-chair of the Financial Regulatory & 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,…
The kind of cases William takes
William reviews new inquiries case-by-case for business, general, and government matters across New York.
Credentials
William B. Mack's legal education and bar admissions
Columbia Law School J.D. 2003 Writing and Research Editor Columbia Law School J.D. Columbia Journal of Law and Social Problems
—
State University of New York at Albany
B.A. · 2000
Jurisdictions
William's state bar admissions
New York U.S. Distri
2004 · ACTIVE
William studied at — in Columbia Law School J.D. 2003 Writing and Research Editor Columbia Law School J.D. Columbia Journal of Law and Social Problems and B.A. in State University of New York at Albany.
Law school and academic background
William completed — in Columbia Law School J.D. 2003 Writing and Research Editor Columbia Law School J.D. Columbia Journal of Law and Social Problems and B.A. in State University of New York at Albany. Formal legal training is one signal of substantive knowledge — the day-to-day practice William runs in New York is where that training gets applied to real client questions.
Affiliations
William's professional memberships and bar associations
Professional & Community Involvement •Member, Chamber of Digital Commerce Task Force on Crypto Asset Trading Platforms •Term Member, Council on Foreign Relations •Board of Directors, Hebrew Language Academy
membership
Locations
William B. Mack's office in New York
William's primary office is at One Vanderbilt Avenue, New York, NY, 10017. In-person meetings are by appointment; a phone intake usually comes first.
Client feedback
Client reviews of William B. Mack
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Schedule your consultationHiring guide
How to hire William B. Mack — what to expect in your first consultation
Working with a new business attorney should feel structured. Here's how the first two conversations with William usually go, from the moment you request a consult to the day representation begins.
Consultation formats and pricing
William charges for the initial consult. That fee is credited toward representation if you retain William's office.
What to bring to your first meeting
Bring any documents you already have — police reports, medical records, filed pleadings, correspondence from an insurer, a copy of the contract at issue. If you're not sure, err on the side of bringing everything; William will tell you what matters and what doesn't.
Questions to ask a business attorney in New York
A short list to run through before you commit: How many business matters have you handled in the last year? What's your fee structure? Who else in the office will work on this? What's your realistic estimate of timeline and range of outcomes? How do I reach you between meetings?
Fees & payment
Fees, payment methods, and consultation options for William
William discusses fees during intake so the arrangement fits the matter. Contingency, hourly, and flat-fee options are all common in business practice — ask which fits.
Hourly rates, contingency fees, and flat-fee options
Every business matter is priced differently. Simple document review might be a flat fee. Injury litigation is often contingency. Complex commercial disputes usually run hourly with a retainer. William confirms the model in the engagement letter before any work starts.
Payment methods and payment plans
William's office accepts standard payment methods. Ask about payment plans if the retainer is a stretch — many business practices work with clients on structured schedules.
Frequently asked
Frequently asked questions about William B. Mack
How much does it cost to hire William for a business case?
Cost depends on the type of matter, the fee model (contingency, flat, hourly), and how contested the case becomes. William walks through the likely range during the consult so there are no surprises.
Does William offer a free consultation?
William charges for the initial consult; that fee is credited toward representation if you retain William's office. Some business attorneys offer free consults — check William's current terms during booking.
How long do business cases in New York typically take?
Simple business matters can wrap in a few weeks; disputed cases can run 6–18 months from intake to resolution, longer if the matter goes to trial. William gives a realistic estimate for your facts at the consult — vague answers here are a red flag.
Can William take my case if I'm outside New York?
William is licensed in New York. Matters governed by New York law are the natural fit. Out-of-state matters are handled case-by-case, sometimes with local co-counsel. Ask during intake — William will tell you if the case is a fit or refer you to someone closer to your court.
What should I bring to my first meeting with William?
Bring every document that touches the dispute: contracts, correspondence, police or medical reports, filed pleadings, invoices, photographs, insurance letters. Also bring a written timeline of what happened, in your own words. William will filter what matters — over-preparing at intake is always cheaper than needing a second meeting.
Is William accepting new business clients right now?
William's intake status shifts week to week. Submit the form; the office will confirm availability or refer the matter out.
Areas served
Business attorneys serving Albany and Brooklyn in New York
William handles business matters throughout New York. Each city below is a direct link into the search page for verified business attorneys in that community.
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