Wall Street heavyweights invited to attend the special summit later today include JP Morgan Chase investment banking chief executive Daniel Pinto, Blackrock chief executive Larry Fink, Goldman Sachs chief financial officer Harvey Schwartz and Morgan Stanley president Colm Kelleher.
It is understood that the American executives want assurances that the rights of their employees based in Britain will be protected once the UK leaves the EU.
The prime minister, who is attending the United Nations General Assembly in New York, has sought to meet them amid concerns that they could be preparing to move their European headquarters out of the UK in the wake of the Brexit vote.
She has also invited the likes of technology behemoths Amazon and IBM, as well as bosses from engineering firms Aecom and United Technologies, and Sony Pictures. Several of these firms are currently engaged in large inward investment into the UK.
The meeting will represent the government's first major interaction with US investors since May came to office earlier this summer.
As well as seeking to reassure the Wall Street giants, May is holding a trade and investment event where she is hoping to encourage around 60 “current and expanding” firms to boost their investment in the UK.
Foreign secretary Boris Johnson is also expected to hold a meeting with business representatives on Wednesday.
Tonight, May also addressed the United Nations General Assembly, where she sought to build a global consensus on measures to tackle human trafficking, as well as entering talks on migration where she defended the right to limit the movement of people.
"We need to be clear that all countries have the right to control their borders and protect their citizens and be equally clear that countries have a duty to manage their borders to reduce onward flows of illegal and uncontrolled migration," May said.
Tomorrow May is due to meet Japanese prime minister Shinzo Abe for talks. In what is set to be a packed US agenda, May is also expected to meet the Prime Ministers of Pakistan and New Zealand, Nawaz Sharif and John Key.
May's Wall Street summit comes after ratings agency Moody's yesterday played down the potential loss of “passporting” rights for UK financial services players, which currently allow firms to operate across Europe.
Moody's said any impact would be limited to internal restructuring, temporary hits to profitability and a diversion of management resources while firms figure out how to operate after Brexit.
"In practice, we expect the impact of a formal withdrawal of the UK from the EEA to be limited for most UK banks," it said.