Shares of publicly traded gun companies fell on Monday, in the first trading session after a massive worldwide rally protesting gun violence. The march was the latest example of strength by supporters of gun-control legislation, which, if passed, could depress the sales and earnings of the sector. The gun-control movement has picked up steam since last month's high school shooting in Parkland, Fla., which left 17 people dead; earlier this month, a number of companies, including Walmart and Dick's Sporting Goods, broke ties with the National Rifle Association. Sturm Ruger & Co. RGR, -2.13% fell 1.6% on the day while American Outdoor Brands Corp. AOBC, -4.50% the parent of Smith & Wesson, fell 3.1%. Both are on track for their third straight daily decline. Also hurting the sector was Remington Outdoor Co., the firearms maker that sought bankruptcy protection Sunday, in the face of a heavy debt load, falling sales and lawsuits tied to 2012 Sandy Hook school shooting. The Dow Jones Industrial Average DJIA, +2.31% jumped 1.8% on Monday while the S&P 500 SPX, +2.11% was up 1.6% and the Nasdaq Composite Index COMP, +2.46% was up 1.8%. Thus far this year, Sturm is down 13% while American Outdoor has shed 26%. American Outdoor recently forecast weak sales for at least a year.