A young girls holds a ballot during the Greek referendum in Athens on July 5, 2015. Greek voters headed to the polls today to vote in a historic, tightly fought referendum on whether to accept worsening austerity in exchange for more bailout funds, in a gamble that could see it crash out of the euro. (Photo by Aris Messinis/AFP Photo)

Boys pan for gold on a riverside at Iga Barriere, 25 km (15 miles) from Bunia, in the resource-rich Ituri region of eastern Congo February 16, 2009. Ituri is one of many areas of the country to have experienced bitter ethnic conflict between rival tribes in recent years. Massacres have left tens of thousands dead. It is this fighting that led U.S. authorities to take the unprecedented step of naming Congo in section 1502 of the Dodd-Frank financial regulation act, which says U.S.-listed companies that source gold, tungsten, tantalum and tin from Congo or its neighbours must assure the U.S. stock exchange regulator that their business is not helping fund conflict. (Photo by Finbarr O'Reilly/Reuters)

Specialist Dilip Patel, left, works at his post on the floor of the New York Stock Exchange, Monday, March 9, 2020. The Dow Jones Industrial Average sank 7.8%, its steepest drop since the financial crisis of 2008, as a free-fall in oil prices and worsening fears of fallout from the spreading coronavirus outbreak seize markets. (Photo by Richard Drew/AP Photo)

Passengers hold 500 (bottom) rupee banknotes to buy train tickets at a railway booking counter in Allahabad, India, November 9, 2016. People are queuing up outside banks across India to exchange 500 and 1,000 rupee notes after they were withdrawn as part of anti-corruption measures. Indians will be able to exchange their old notes, which stopped being legal tender at midnight on Tuesday, for new ones at banks until 30 December. The surprise move is part of a government crackdown on corruption and illegal cash holdings. Banks were shut on Wednesday to allow them enough time to stock new notes. There are also limits on cash withdrawals from ATMs. The BBC's Yogita Limaye in Mumbai says there have been chaotic scenes outside many banks. (Photo by Danish Siddiqui/Reuters)

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)

A child working at Ship breaking yard in Chittagong, Bangladesh on November 14, 2014. (Photo by Pascal Mannaerts/Alamy Stock Photo)

A Saudi trader wears a mask as he monitors stock information at the Saudi stock market in Riyadh, Saudi Arabia on August 25, 2020. (Photo by Ahmed Yosri/Reuters)

A man sits waiting for a train on the London Underground in 1890, when the platform floors were still made from wooden floorboards. (Photo by Hi-Story/Alamy Stock Photo)