A participant of the Castle Party festival poses for picture as a man walks past in Bolkow, southwestern Poland, July 16, 2015. The annual festival features around 50 musicians and artists playing on various stage Gothic rock and other styles of the dark music subculture. Outside Germany, it is one of the biggest festival with this genre of music, the event attracts regular international audience of up to 5000, the organizers said. (Photo by Kacper Pempel/Reuters)

Thousands of revelers continue to enjoy themselves throughout the night on Sunrise Beach on February 25, 2005 in Haadrian, Koh Phangan. (Photo by Shaul Schwarz/Getty Images)

Christopher Walken, Angelo Galasso and Clint Eastwood attend the premiere of Jersey Boys in New York June 9, 2014. REUTERS/Andrew Kelly

A woman dives and pretends to ride a bike in Underwater Park in Pula, Croatia, August 1, 2017. (Photo by Antonio Bronic/Reuters)

The snitch runner takes the broom from between the legs of a Werewolves of London quidditch player during the Crumpet Cup quidditch tournament on Clapham Common on February 18, 2017 in London, England. (Photo by Jack Taylor/Getty Images)

Some are in it just for the money, others to help buy a meal. Then there are those who trade for fun or to spend time among friends. Millions of investors – pensioners, security guards, high-school students – dominate China's stock markets, conducting about 80 percent of all trades. Retirees gather in brokerage houses dotted around China also to enjoy some company and savour the air conditioning on hot days. Some start as young as 13, trading from home with an eye on future careers in finance. Winning isn't guaranteed. This year, among the most turbulent in China's financial history, its stock markets more than doubled in the six months to May, only to crash amid concerns that growth in the country, which makes everything from cars to steel, is slowing faster than previously thought. (Photo by Aly Song/Reuters)