It happened in December 2015 when two assailants killed 14 people and wounded 22 others in a shooting in San Bernardino.

It happened again in June 2016 when 49 people were killed and 58 injured in Orlando, Florida, after a gunman stormed into a packed gay nightclub.

And it's happened again this week following Sunday's attack at a Las Vegas concert - the deadliest mass shooting in modern US history - which has so far taken at least 59 lives and injured more than 500 people.

Since the election of US President Donald Trump - who made upholding the right to bear arms a central plank of his 2016 election campaign - fire-arm company stocks have been sluggish.

But following Sunday's attack, shares of US gunmakers jumped more than 3 per cent. By Monday, firearm manufacturing company Sturm, Ruger & Co, climbed 3.5 per cent. Smith & Wesson parent American Outdoor Brands, which makes and sells pistols, revolvers and rifles, finished up more than 3 per cent. And Vista Outdoor, which sells firearms and ammunition, was up almost 3 per cent.

Gary Kaltbaum, president of investment firm Kaltbaum Capital Management, said the rise in gun stocks is both due to the perception that gun controls could tighten and restrict the availability of weapons, as well as a belief that gun buying will pick up as Americans look to "protect" themselves.

The pain of the attack is also being felt at MGM Resorts International. MGM Resorts is owner of the Mandalay Bay resort, where the gunman, Stephen Paddock, 64, was staying and its shares fell almost 6 per cent following the attack.

The gunman who unleashed hundreds of rounds of gunfire on a crowd of concertgoers in Las Vegas attached what is called a bump-stock to two of his weapons, in effect converting semiautomatic firearms into fully automatic ones. Photo: AP

Paddock, who opened fire on spectators at the Route 91 Harvest Festival, was reportedly able to take a series of firearms past security and up to his room at 32nd floor, where he was later found dead from a self-inflicted gunshot wound.

MGM's chairman and chief executive, Jim Murren said in a statement that the company was "cooperating with law enforcement and taking actions to support the victims and their families, our guests and employees".

Headquartered in Las Vegas, Nevada, MGM also owns other properties in the iconic Las Vegas strip including Bellagio, ARIA, Vdara, MGM Grand, Delano Las Vegas, The Mirage, Monte Carlo, New-York New-York, Luxor, Excalibur, and Circus Circus.

Drapes billow out of broken windows at the Mandalay Bay resort and casino Monday, Oct. 2, 2017, on the Las Vegas Strip following a deadly shooting at a music festival in Las Vegas. Photo: AP

Instinet analyst Harry Curtis, said in a note to investors that the company was likely to see elevated cancellations over the next several weeks or months and higher security costs, but recommended investors hold onto the stock.

Shares of other casino operators also fell on Monday after the massacre. Wynn Resorts dropped almost 2 per cent. Caesars Entertainment Corporation pulled back 0.2 per cent. Las Vegas Sands also dipped before closing slightly higher on Monday.

Tourism to Las Vegas hit an all-time high of 42.9 million guests last year, a 1.5 per cent increase from 2015. Apart from the obvious detrimental tourism implications, the massacre has raised questions about hotel security and whether tougher measures are now needed.

-with Bloomberg

Follow Nassim Khadem on Facebook and Twitter.