PricewaterhouseCoopers is forecasting that London is set to eclipse Paris and Chicago as the fourth biggest economy among world cities by 2020, as reported by the BBC, so it's no surprise that the massive growth in business and financial services is expanding the ranks of the mega-rich.

With all the money sloshing in to London, the "haves and have yachts" are growing, reports MSNBC via the Washington Post.

Rich London bankers and traders who think nothing of spending tens of thousands on a night out, or on tailors, jewelers and personal concierges, are doing pretty well thank you very much. "The adrenaline rush you get from making a 10 million-pound bonus is the same as falling off a cliff at 3,000 feet," says one businessman.

And it's not just in London. The number of billionaires around the world is growing. Strong equity markets combined with rising real estate values and commodity prices have pushed up fortunes all round the globe, from Moscow to Mumbai. There are now 946 billionaires around the world and their combined wealth has now hit $3.5 trillion, report the fortune hunters at Forbes. Alternatively, you can read the Forbes report here via USA Today.

Not only are there more billionaires, but two thirds of them are richer.

Bill Gates and Warren Buffett head the list but with the way those two are giving away their fortunes, who knows how long they'll be holding down top spot.

There are 178 new newcomers including 19 Russians, 14 Indians, 13 Chinese and 10 Spaniards. The first billionaires from Cyprus, Oman, Romania and Serbia have also made it on to the list.