After four weeks of focus on Wall Street, the campaign against the global banking industry is coming to the UK this weekend, with the biggest event aiming to "occupy" the London Stock Exchange.

The protests have been organised on Facebook and Twitter pages that between them have picked up more than 15,000 followers. Campaigners are to gather outside St Paul's Cathedral at midday on Saturday before marching the short distance to Paternoster Square, home of the Stock Exchange, as well as the London head office of investment bank Goldman Sachs.

It is one of a series of events planned around the UK as part of a global day of action, with 800-plus protests promised so far worldwide.

It remains to be seen how many of the online supporters will turn up in London, with estimates ranging from a few hundred to a couple of thousand. It is also unclear whether the City police, the small force that operates in London's financial district, will permit activists to mimic the Wall Street protests by pitching tents.

Paternoster Square is a private development, giving police more powers to remove activists. Among its tenants are a number of upmarket shops and restaurants that may take a dim view of a semi-permanent encampment.

The force refused to discuss whether protesters would be moved on, saying only that "appropriate policing preparations are in place". The Stock Exchange and Goldman Sachs declined to comment.

The current protests – which combine anger at the bailout of the financial sector with disquiet at the faltering global economy and increased inequality – have their roots in mass marches earlier this year in Spain. They have attracted global attention with the camp in Manhattan's Zuccotti Park, which was scheduled to be cleared by authorities on Friday.

The first UK event took place in Manchester this month, timed to coincide with the Conservative party conference in the city. Up to 30 people remain in tents in the city's Peace Gardens in St Peter's Square. About a dozen other events are planned for Saturday around the UK, including Birmingham, Leeds, Bristol, Norwich, Glasgow and Edinburgh.

Among events in other countries, 1,300 people have pledged via Facebook to occupy a central plaza in Sydney, with similar events planned for Saturday in Melbourne, Taipei, Seoul and Hong Kong. The global movement has issued a manifesto, endorsed by Naomi Klein and Noam Chomsky, among others, calling for a democratisation of the global finance system and mentioning the Arab spring as an inspiration for mass action.

One protester planning to take part in London said the campaign, which is not allied to any political party, began with a series of Facebook pages in early September. Once people gathered at the Stock Exchange there would be mass votes to decide the next course of action, said Spyro Van Leemnen, 28.

"All decisions on the occupation, and how we're going to take it forward, will happen then. If people decide they don't want to stay then that's it, we won't stay," he said, adding that he was bringing a tent in the expectation of staying for some time. "The idea is to stay there as long as it takes to see some substantial change. No one said it would be easy," he said. "Since 2008 these ideas have been building up, and I think people realise there will be no governments who will represent their interests against the banks, unless the people themselves raise their voices." Another activist planning to go to St Paul's, Peter Vaughn, 24, said the aim was to set up a "rolling camp" of protesters as a permanent symbol of people's concerns. "When the crisis began I think people were patient. They were told, 'We need to bail out the banks, this is the only way to save our economy.' And now the whole European economy is in crisis, while banks continue to pay bonuses. The situation is untenable." Vaughn said he hoped the police would permit them to remain, but was aware that TV footage of protesters being dragged away could publicise the campaign: "We're not going there for a fight with the police. This is about legitimate concerns that we have."

A history and politics graduate who had worked for two years as a bicycle courier because of a lack of better options, Vaughn said there was also a personal element to his participation: "I feel like graduates were sold a lie. We're not the ones that are suffering the most, but from a personal view, we were told, 'You take on this debt but you'll get a job and pay it off.' I'm still more than £10,000 in debt."

There has been little response so far from the global finance industry, although the US-based chief executive of Citigroup, Vikram Pandit, said this week he would meet the Wall Street occupiers, calling their views "completely understandable".

Brian Mairs, of the British Bankers' Association, said he knew of no similar plans in the UK. However, he said his organisation did not rule out engaging with protesters: "If there is a forum to have a sensible discussion, we would be happy to do it."