He is a faculty member in the Finance Department at Boston University Questrom School of Business where he teaches courses in banking, capital markets and FinTech.

In 1997 he joined Citizens Power LLC, a Boston-based energy trading company and became a senior vice president, Head of Global Risk Management.

[3] Williams is a member of the Standard & Poor’s Academic Council, a senior advisor at the Brattle Group[4] and is on the advisory board of Appleton Partners, a Boston-based private wealth management firm.

[26][27][28] In 2019, Williams completed a performance study on Major League Baseball Umpire's pitch-call accuracy over 11 seasons (2008-2018) concluding that over 20% of certain pitches were called incorrectly.

[34] He raised concerns about Bitcoin, including lack of consumer protection, it being a high-risk virtual commodity, having an artificially inflated price, extreme hoarding, hyped demand, high potential for market manipulation, and fraud.

[37] He was a speaker at the World Bank Law, Justice and Development (LJD) Week October 2014[38] where he discussed virtual currencies and the regulatory and legal challenges of new peer-to-peer technologies in financial services.