For the purpose of this market, a “mass shooting” is defined as an event involving the intentional use of firearms to harm multiple individuals, leading to at least 20 victims who are killed in the incident. The count of fatalities will exclude the shooter(s) involved in the attack.

The event must be confirmed by credible news sources and official law enforcement reports, specifying the number of fatalities.

• **Yes**: A mass shooting with more than 20 fatalities (excluding the perpetrator(s)) will occur in the US/US territories in 2024.

• **No**: No mass shooting with more than 20 fatalities (excluding the perpetrator(s)) will occur in the US/US territories in 2024.

Please note that incidents occurring as part of organized crime, gang conflicts, or terrorist attacks are included as long as they meet the specified criteria for fatalities.

All I'm saying is if you put 50K on YES, I'm calling the cops.

In the past 14 years (168 months) there have been 6 shootings meeting the criteria[1], meaning there's a (1-6/168)*100 = 96.429% chance that there ISN'T a mass shooting meeting the criteria per month, and since there are 7 months left in 2024 that means the probability that there ISN'T a shooting is 0.96429^7 = 77.525%, so the answer to the question should be 22%.

[1] https://en.wikipedia.org/wiki/List_of_mass_shootings_in_the_United_States

Updated probability: Shooting rates are trending upwards, so if you instead take a linear regression of the shootings meeting the criteria and plot that, you'll get the equation y=0.01758x-35.02637 where x is the year and y is the number of shootings. Extrapolating out to 2024 shows that there should be 0.556 shootings meeting the criteria in 2024 (which doesn't quite correspond to the question probability due to the chance of having 2 shootings in a year, but we'll assume it's perfect), and if you split that into months by taking the 12th root of 1-0.556, raising it to the 7th power, and inverting it again, you get 0.37726, so the more accurate answer to the question should be 37%.