Citigroup Inc said on Thursday that they will add restrictions on firearms sales for new retail-sector clients. This is the strongest move to date by a major U.S. lender following last month's high school shooting in Florida. In an e-mailed statement Citi said it will require those clients only sell firearms to customers who have passed a background check, restrict sales of firearms for people under 21 years of age, and not sell so-called “bump stocks” or high-capacity magazines.