Location, Location, Location presenter Phil Spencer, actress Joanna Lumley and London mayor Sadiq Khan took to the trading floor in a charity event commemorating the 9/11 terrorist attacks.
It was a "fantastic" experience for Spencer, who took a day out from his usual job as a property expert to try his hand at the world of stocks.
He said: "I've never been on a trading floor, so I didn't know what to expect.
"I was a bit apprehensive but the guys talked me through everything and I thoroughly enjoyed it.
"So far I have done three or four trades. I just lent someone £50 million until tomorrow - which sounds like a big number to a layman."
But Spencer is not planning a career change just yet, as he said the skills involved on the trading floor did not play to his strengths.
He added: "These guys and girls are sharp, but maths was never my strong point at school. And they can use two phones at once, which is probably a bit difficult for me."
The event on Monday was held at the office of BGC Partners in Canary Wharf, east London.
The American financial services company, which was originally based in the World Trade Centre, lost 658 members of staff during the 9/11 terrorist attacks.
BGC first launched an annual charity day 12 years ago to raise money to support the families of its staff members who died.
Now the event sponsors more than 20 UK charities by inviting celebrities into the firm's London office to have a go at closing telephone trade deals.
All proceeds from those deals are donated to organisations such as British Heart Foundation, Make-A-Wish and Battersea Dogs & Cats Home.
The office floor was full of action as the celebrity guests moved between telephones, and there were onstage interviews with comedians John Bishop and Romesh Ranganathan.
Other guests throughout the day included actor Tom Hardy, US actress Lindsay Lohan, comedians Russell Howard and Al Murray, TV illusionist Dynamo and a number of Olympic athletes.
Pippa Middleton was also set to have a go on the trading floor later in the afternoon.