Iraqi firefighters try to stop the fire of burning oil wells in Kirkuk, northern Iraq, 02 June 2016. Two Khabbaz oil field wells in Kirkuk Province, northern Iraq, exploded by suspected insurgents, a security official said. (Photo by EPA/Stringer)

People attend in costume the 2022 New York Comic Con, at the Jacob Javits Convention Center in Manhattan in New York City, New York, U.S., October 6, 2022. (Photo by Brendan McDermid/Reuters)

Jockey student Mariangelys Almedina (Front) balances on a steel drum suspended in the air by a series of springs to simulate riding a horse as Instructor Willie Lozano looks on at the Vocational Equestrian Agustín Mercado Reverón School located in the Hipódromo Camarero on November 17, 2022 in Canovanas, Puerto Rico. The Vocational Equestrian Agustín Mercado Reverón School has produced some of the best jockeys in the world but also prepares students for a wide range of equestrian jobs on a tuition-free basis. (Photo by Al Bello/Getty Images)

This incredible panoramic photographs are distorted to create miniature worlds and terrifying tunnels. (Photo by Caters News)

Russia's Maria Sharapova carries the torch during the opening ceremony of the 2014 Winter Olympics in Sochi, Russia, Friday, February 7, 2014. (Photo by Matt Dunham/Associated Press)

An “asparagus eating contest” made of asparagus and carved pumpkins is on display on the sidelines of the Giant Vegetable Competition in Klaistow, northeastern Germany, on September 20, 2015. The vegetable giants compete in seven categories. (Photo by Bernd Settnik/AFP Photo)

Yanelis Blanco, 24, center, dances with a group of friends at Santa Maria beach, about 15 miles from Havana. It is the closest beach to Havana. Others, from left to right are Jackson Miranda, 21, Dayan Suarez, 24, and Melisa Oliva, 15. The men in the group have a rap group together. The government is demolishing buildings all over the coast of East Havana and recovering and restoring beach dunes. (Photo by Sarah L. Voisin/The Washington Post)

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)