Mr. Burr’s remained open months longer.
Though he did not contest that he sold much of his portfolio out of concern for the spreading pandemic, he insisted that his trades were based entirely on information reported by financial news outlets in Asia, not special briefings he received as a senator.
Insider trading cases — particularly those involving lawmakers — are notoriously difficult to prove. Lawmakers, like any other citizen, are allowed to make investment decisions based on public information. Under the 2012 Stock Act, they are prohibited from making decisions based on specific, nonpublic information they access as senators.
The challenge for investigators is teasing out public from nonpublic information with enough confidence to prove that a lawmaker like Mr. Burr acted with an unfair advantage over other investors. That is made even more difficult by the Constitution’s speech or debate clause, which gives members of Congress unusual protections from investigators.
In this case, Mr. Burr’s sales came just days after a series of briefings he received as a member of the Senate’s intelligence and health committees in late January and early February focused on the coronavirus threat. At the time, Mr. Trump and members of his party were downplaying the virus threat and, though it had spread widely in Asia, the pandemic had yet to greatly affect American life or its financial markets.
Mr. Burr, who had long trained his eye on public health and warned about the threat of pandemics, clearly took it more seriously. On Feb. 13, he sold 33 stock holdings, worth a collective $628,000 to $1.7 million, a large share of his portfolio.
The timing allowed him to avoid losses other investors incurred when the stock market sharply contracted in February and March. The financial markets have since recovered and are scraping record highs.
There were other costs for Mr. Burr along the way. He stood on the sidelines, for instance, when the Intelligence Committee this summer delivered the final results of its yearslong inquiry into Russian election interference in 2016 and ties to the Trump campaign. He had overseen the politically sensitive investigation from its outset, working closely with the panel’s top Democrat, Senator Mark Warner of Virginia, in the face of sharp objections by President Trump, winning respect from colleagues in both parties.