The world's biggest investment management firm, BlackRock Inc, is stepping up pressure on companies that make and sell guns in response to the Florida school shooting.
It is considering excluding them from some of its portfolios and is asking how they monitor safe use of weapons.
The US corporation said the Florida shooting on 14 February, in which 17 people died, required a response.
Walmart and Dick's Sporting Goods announced curbs on gun sales earlier.
"As it has for many people, the recent tragedy in Florida has driven home for BlackRock the terrible toll from gun violence in America," the corporation said on its website.
"We believe that this event requires response and action from a wide range of entities across both the public and private sectors."
A growing number of companies have cut ties with America's main gun lobby, the National Rifle Association (NRA).
United and Delta airlines recently joined car rental giants Hertz and Enterprise in ending discounts for NRA members.
Nikolas Cruz, 19, is in custody, suspected of the mass killing at his former high school in Parkland, Florida.