Shares in US gun manufacturers rallied strongly after the horrific murder of at least 59 people in Las Vegas.

American Outdoor Brands closed up 3.2 per cent on Monday after news broke of the attack in which more than 500 people were also injured. The shares were maintaining those gains on Tuesday.

Sturm Ruger, America’s largest firearms manufacturer, was up 3.6 per cent on its price before the Las Vegas shooting in morning trading in New York on Tuesday. Olin, which owns the Winchester ammunition brand has also enjoyed gains.

The phenomenon is, sadly, one too frequently witnessed in recent years. A 2016 analysis by hedge fund Quantopian tracked share price data in the aftermath of 20 events, including 12 mass shootings since 2007 as well as actions by Barack Obama on gun control.

An algorithm calculated that an investor who bought shares in Smith & Wesson and Sturm Ruger on the day after one of these events then sold them 90 days later would have netted a return of 365 per cent over a nine-year period, compared to 66 per cent for the S&P 500 Index over the same timeframe.

US firearms manufacturers frequently do well after mass shootings or threats of a regulatory crackdown.

The logic behind this is that atrocities will put pressure on authorities to push through tougher firearms laws. Therefore, panicked gun-lovers go out and buy more weapons, fearing that their ability to do so in future will be restricted.

But past experience shows that significantly tighter gun regulations have been difficult to pass, meaning that gunmakers get a short-term boost to sales without the long-term pain associated with tougher laws. Mass murders using guns have in some respects been good for gunmakers' business in recent years.

US president Donald Trump has repeatedly said he loves the Second Amendment which lays out the right to bear arms. And since becoming president, he has begun rolling back restrictions on gun sales.

Last month, gun manufacturers' shares jumped on the back of reports that Mr Trump was planning to relax rules on sales of American firearms around the world.

Four senior US officials told Reuters at the time that the President intends to shift control of non-military weapons sales outside the US from the security-focused State Department to the trade-focused Commerce Department.

Las Vegas shooting – in pictures Show all 15 1 /15 Las Vegas shooting – in pictures Las Vegas shooting – in pictures People scramble for shelter at the Route 91 Harvest country music festival after gun fire was heard Getty Las Vegas shooting – in pictures People carry a person at the Route 91 Harvest country music festival after shots were fired David Becker/Getty Las Vegas shooting – in pictures People run from the Route 91 Harvest country music festival after gun fire was heard David Becker/Getty Las Vegas shooting – in pictures A handout photo released via Twitter by Eiki Hrafnsson (@EirikurH) showing concertgoers running away from the scene (C) after shots range out at the Route 91 Harvest festival on Las Vegas Boulevard EPA/Eiki Hrafnsson Las Vegas shooting – in pictures People lie on the ground at the Route 91 Harvest country music festival after hearing gun fire Getty Las Vegas shooting – in pictures A man in a wheelchair is taken away from the Route 91 Harvest country music festival after hearing gun fire David Becker/Getty Las Vegas shooting – in pictures People stand on the street outside the Mandalay Bay hotel near the scene of the Route 91 Harvest festival on Las Vegas Boulevard EPA/Paul Buck Las Vegas shooting – in pictures FBI agents confer in front of the Tropicana hotel-casino after a mass shooting during a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Las Vegas police run by a banner on the fence at the Route 91 Harvest country music festival grounds after shots were fired David Becker/Getty Las Vegas shooting – in pictures An injured person is tended to in the intersection of Tropicana Ave. and Las Vegas Boulevard after a mass shooting at a country music festival Ethan Miller/Getty Las Vegas shooting – in pictures Metro Police officers pass by the front of the Tropicana hotel-casino after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures A woman sits on a curb at the scene of a shooting outside of a music festival along the Las Vegas Strip AP/John Locher Las Vegas shooting – in pictures A cowboy hat lays in the street after shots were fired near a country music festival in Las Vegas Getty Las Vegas shooting – in pictures Las Vegas Metro Police and medical workers stage in the intersection of Tropicana Avenue and Las Vegas Boulevard South after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Sheriff Joe Lombardo (2-R) speaking during a press briefing in the aftermath of the active shooter incident on Las Vegas Boulevard EPA

In February, about a month after he was inaugurated, Mr Trump signed a resolution blocking an Obama-era rule that would have prevented an estimated 75,000 people with mental disorders from buying guns.