Citigroup Acted. Now, Two New Ideas on How Banks Can Limit Gun Sales.

On Saturday afternoon, as hundreds of thousands of people joined the March for Our Lives around the nation, I was on the phone with Michael Corbat, chief executive of Citigroup.

Mr. Corbat had taken the remarkable step on Thursday of authorizing a new set of rules to restrict gun sales by Citi’s clients, the first time a Wall Street bank had used its position to influence the gun control debate.

Five weeks earlier, a gunman’s attack at a high school in Parkland, Fla., had left 17 dead. Soon afterward, I wrote a column challenging the business world to “effectively set new rules for the sales of guns in America,” given Washington’s intransigence.