Three business days after Mr. Ross was contacted by The New York Times for a forthcoming article about those ties, he took out a short position valued at between $100,000 and $250,000 on Navigator’s stock — essentially a bet that the stock’s value would decrease — putting him in a position to potentially profit from negative news about the company. The company’s stock price fell roughly 4 percent before Mr. Ross closed his position, 11 days after The Times and the International Consortium of Investigative Journalists published an article on his ties to Navigator.

In a response in June, Mr. Ross said that the information the reporter had contacted him about was not “market-moving” and that making money was not the goal of the short sale.

The letter from the Office of Government Ethics also cited Mr. Ross for failing to sell stock in a company called Invesco, the parent company of his private equity firm, W.L. Ross & Co., in keeping with his ethics agreement. Mr. Ross signed a form in November 2017 saying he had completed divestitures that he had agreed to earlier that year, but in December, he submitted a report revealing that he had not sold the Invesco stake until Dec. 19-20.

The office said that an internal Commerce Department investigation that reviewed Mr. Ross’s calendars, briefing books and correspondence did not indicate the presence of a criminal violation, and that it had no evidence to contradict Mr. Ross’s argument that the omissions and inaccuracies were inadvertent. However, it added that even inadvertent errors could damage public trust and violate criminal conflict of interest law. Federal ethics rules prohibit government employees from using information they view in the course of their work for private profit.

“It is a serious matter, particularly when you’re dealing with someone like the secretary of Commerce, who has his finger on so many decisions that affect businesses and financial investments,” said Richard Briffault, a professor at Columbia Law School.

Senator Ron Wyden, an Oregon Democrat, called on the Justice Department to investigate the transactions.

“The top federal ethics watchdog confirmed what anyone with eyes and ears already knew: Wilbur Ross’s stock trades seriously compromised his ability to act in America’s best interests, and may have broken the law,” Mr. Wyden said. “In light of this report, the Justice Department should conduct a thorough investigation to ensure that Ross was working on behalf of all Americans and not just his own bank account.”