Stocks in gun companies have been dragged lower by a cloud of negativity after last week's mass shooting at a Florida high school, which continues to dominate public debate.

Shares of American Outdoor Brands (AOBC), the company formerly known as Smith & Wesson, have dropped 8% since the day after the shooting. Vista Outdoor (VSTO), which makes guns and ammunition, has declined 7%. Sturm Ruger (RGR) is down slightly. All while the broader market has risen.

The declines are the result of the backlash surrounding guns, according to Brian Rafn, a gun industry analyst for Morgan Dempsey, following the tragedy that left 17 dead in Parkland, Florida, on Valentine's Day.

"The constant negativity, the constant rhetoric, the drum beat could have some peripheral institutional investors saying 'enough of this,'" said Rafn. "There are some institutional investors who are going to say, 'There's got to be greener pastures.'"

Related: BlackRock wants to have a talk with Ruger, Vista and American Outdoor Brands

Rafn said that many gun investors are gun enthusiasts and military veterans who will probably stick with their long-term investments in the industry. But other investors, particularly institutional investors that don't have a philosophical attachment to guns, are losing their stomach for the industry.

BlackRock, the giant investment management firm, is the largest shareholder in Sturm Ruger and American Outdoor Brands and the second-largest shareholder in Vista Outdoor.

In a statement Thursday, BlackRock said it "will be engaging with weapons manufacturers and distributors to understand their response to recent events."

The National Rifle Association has also been criticized intensely over the last two weeks, and a number of big brands have severed their ties with the organization. First National Bank of Omaha said it will stop issuing its NRA-branded Visa card, while six different car rental brands, including Enterprise, Alamo, Hertz and Budget are discontinuing their discount programs for NRA members.

Related: This is why mass shootings no longer drive gun sales

At the same time, two gun safety groups are pressuring Appl, (AAPL) Amazo, (AMZN)Googl an (GOOG)d Roku to remove NRATV, a pro-gun video channel from their streaming platforms, while Twitter users are circulating the hashtag #StopNRAmazon.

And Republican politicians appear to be softening on gun control. Both Florida Governor Rick Scott and Senator Marco Rubio have suggested raising the minimum age to buy a gun from 18 to 21. Scott also suggested a ban on bump stocks. Rubio, who has accepted funds from the NRA, said he was open to considering limitations on magazine capacity.

In addition to the bad publicity, the gun industry is suffering from weak sales. Sturm Ruger reported a double-digit decline in sales and earnings on Wednesday and said it cut 700 jobs over the last year. Remington, another major gun maker, said last week that it is preparing to file for Chapter 11 bankruptcy protection.

The threat of imminent gun control measures helped boost sales during the Obama administration, and Hillary Clinton's campaign. But that threat has faded considerably now that Republicans control both the White House and Congress.

-- CNNMoney's Julia Horowitz contributed to this story.