It isn’t clear how many of the NRA’s nearly five million members hold the credit card. Representatives of the NRA didn’t immediately return request for comment. The Second Amendment-rights organization continues to offer a prepaid card, issued by Republic Bank & Trust Co. The bank didn’t reply to request for comment on the matter.

An increasing number of institutions, be they pension funds or municipalities, are demanding that their portfolios exclude companies that make guns and other weapons. Many of the funds, such as the giant CalSTRS, represent one of the groups most affected by school shootings: teachers.

More than $845 billion of U.S. institutional assets restricted investments were in weapons as of the start of 2016, according to data from US SIF, the Forum for Sustainable and Responsible Investment. That number soared more than 1,000 percent following the Sandy Hook school shooting in December 2012, from $74 billion at the start of 2012.

Rommel Dioonisio, managing director of research at Aegis Capital Corp., said that given the outcry over the latest shooting, “it would certainly not surprise me to see other state funds divest their investment holdings in the industry.” Still, that might not depress gun stocks given other investors will probably still be willing to buy them.

For the moment, holders are not just dumping shares of gun makers. Some are trying to exert pressure from within: Shareholders have filed at least three proposals at sellers or makers of guns in the current proxy season. The proposals ask American Outdoor Brands Corp., maker of Smith & Wesson; Dick’s Sporting Goods Inc.; and Sturm Ruger & Co. to report on steps they’re taking to improve gun safety and to mitigate the harm associated with gun products.

The proposals were filed by religious groups affiliated with the Interfaith Center on Corporate Responsibility, whose members includes 300 institutional investors that manage $400 billion in assets.

Some institutions, such as BlackRock which manages $6.3 trillion, are privately contacting gun companies to make their case.

“Given our inability to sell shares of a company in an index, even if we disagree with management, we focus on engaging with the company and understanding how they are responding to society’s expectations of them,” said BlackRock spokesman Ed Sweeney. "We will be engaging with weapons manufacturers and distributors to understand their response to recent events.”

He added that BlackRock works with clients who want to exclude weapons makers from their portfolios. BlackRock manages more than $200 billion of assets that are screened for weapons ownership and other value-based issues.

Larry Fink, BlackRock’s CEO, wrote to portfolio companies last year, warning that in addition to making money, they must also be aware of the impact on society.