Mass shootings in America are historically followed by a sharp rise in gun sales, according to a working paper out of Harvard Business School.

After Sunday’s mass shooting in Orlando, New York Stock Exchange stock prices for Smith & Wesson and Sturm, Ruger & Co.—two major gun manufacturers—both had risen by more than 10 percent combined, according to Vox. And that trend isn’t unique to this weekend’s shooting.

Experts believe people go out to buy guns because of either fear for their own safety or fear that gun control laws will pass because of the tragedy and they won’t be able to purchase the gun in the future.

Wunderlich analyst Rommel Dionisio told NBCNews that those reasons also determine which guns people go out to buy.

“When people are concerned about their own safety, they go buy handguns. Right after Newtown, Obama and Biden got out there and tried to ban assault rifles. It wasn’t so much then a fear for safety. It was more the fear that the administration would ban a certain kind of gun.”

Historically, mass shootings don’t usually lead to stricter regulation on gun control laws—they actually loosen them in states with Republican legislatures. In Republican-controlled legislatures, the number of laws proposed to loosen gun control increased by 75 percent, where in Democrat-controlled legislatures, the number of laws proposed to restrict gun access increased 10 percent, according to the Harvard Business School study.

The major distinction in this case was the magnitude of this shooting, so it’s hard to predict whether the trend will continue to hold in the aftermath of this shooting as well.