Prince William and Prince Harry have become stockbrokers for the day, making deals over the phone on the trading floor of the BGC offices in London's Canary Wharf.
The princes took part in the BGC Partners annual Charity Day on the 12th anniversary of 9/11 to raise money in memory of the 658 BCG workers in New York who died in the World Trade Centre attacks.
"It's because of the affect they had on all of us that Charity Day is able to help as many people as it does and we will be forever thankful to have known them," said the company.
The princes tried their hand at playing the stock market to raise money for more than 100 charities worldwide, including SkillForce and WellChild, of which William and Harry are patrons respectively.
They assisted the traders by making telephone calls and business deals.
Harry took part in the 2011 event and William did the same the previous year.
At the 2011 Charity Day, Harry broke the world record set by his brother for the largest foreign currency trade after closing a foreign exchange deal worth £15.5bn.
Celebrities joining the princes in playing the market for the 2013 charity Day included Idris Elba, Penny and Rod Stewart, Rob Brydon, Chris Evans and Cerys Matthews.
Since the day was launched in 2004, BGC partners has raised £56m. All global revenues earned on the day go to charitable causes.
In 2012, the event raised £7.6m and was attended by Princess Beatrice, Mo Farah, Harry Redknapp, Alastair Campbell, Joan Collins and Lewis Hamilton.