The husband of a former House speaker, Paul Pelosi, sold more than $500,000 worth of Visa stock just months before the company faced antitrust charges from the federal government, according to a new report.

The tech entrepreneur behind the “Nancy Pelosi Stock Tracker” account on X, Christopher Josephs, posted a screenshot of a congressional filing on July 3 indicating that Mr. Pelosi had sold 2,000 shares of Visa, valued at between $500,000 and $1 million, Fox News reported. The disclosure form marked the transaction as “SP,” denoting it was conducted by Speaker Nancy Pelosi’s husband.

On Tuesday, Visa was sued by the Department of Justice’s antitrust unit for allegedly monopolizing the debit card market. The lawsuit claims that Visa used its dominant position to penalize customers and merchants who chose competing payment processors. Additionally, it alleges that Visa threatened financial technology firms, coercing them to work exclusively with the company.

A representative of the former speaker issued a statement saying, “Speaker Pelosi does not own any stocks, and she has no prior knowledge or subsequent involvement in any transactions.”

The same July 3 disclosure document also showed that Mr. Pelosi sold 2,500 shares of Tesla and purchased stock in Nvidia and Broadcom. Earlier this year, the Pelosis made nearly $4 million over a six-month period via investments Mr. Pelosi made in Nvidia.

In 2022, Mr. Pelosi spent more than $1 million on Nvidia call options just weeks before a congressional vote on whether to give the company huge subsidies, but he sold them after the story broke.

Ms. Pelosi, who has a significant net worth due to her and her husband’s extensive stock and investment portfolio, continues to be a key figure in the Democratic Party despite having to step down as speaker last year after the Republicans took control of the House. She has consistently resisted calls from lawmakers to ban legislators and their spouses from trading stocks, citing conflicts of interest.