Bad news travels fast, and so does rage, according to scientists at Beihang University in China.
Researchers evaluated millions of messages posted to Sina Weibo, a Chinese micro-blogging site similar to Twitter, and tracked the emoticons used in them.
They found that while joy spreads faster than sadness or disgust, nothing is speedier than anger.
Sina Weibo users reacted most quickly and harshly to reports concerning "social problems and diplomatic issues," such as a 2010 event in which a tainted food additive was linked to a disease.
Researchers found that messages posted to the site triggered chain reactions of outrage that spread into a wider and wider circle.
According to the study's authors, it seemed users were not only expressing their anger but also seeking to instill a shared sense of outrage in their online community.
Scientist at the University of Pennsylvania reached a similar conclusion in 2013 after analyzing 7,000 New York Times stories during a three-month period to see which ones were the most shared.
They found that the likelihood of sharing content involved how "activated" a person felt after reading it.
While sadness is a "deactivating" emotion that makes people want to withdraw, anger is an "activating" feeling.
"Anger is a high-arousal emotion, which drives people to take action," study author Jonah Berger told the Smithsonian. "It makes you feel fired up, which makes you more likely to pass things on."
The only emotion Berger found that led to viral content more often than anger was awe.
In his book, "Contagious: Why Things Catch On," he writes that science articles have a high probability of spreading because they "frequently chronicle innovations and discoveries" that evoke a feeling of awe in readers.
"Awe gets our hearts racing and our blood pumping," he said. "This increases our desire for emotional connection and drives us to share."