Britain's prime minister pitched the benefits of the London Stock Exchange during a visit to Saudi Arabia on Wednesday as the kingdom weighs which international market to list shares of oil giant Aramco in what many expect will be the largest public offering in history.

Theresa May made her pitch in the capital, Riyadh, during the second and final day of her visit. Saudi Arabia plans to list less than 5 percent of the world's largest oil-producing company on the Saudi exchange and another international exchange, possibly by next year.

May met with King Salman and separately with his son, Deputy Crown Prince Mohammed bin Salman, who is also defense minister and second-in-line to the throne.

May's Downing Street office said that in a meeting with Saudi Aramco Chairman and Oil Minister Khalid al-Falih she laid out the advantages of doing business in the U.K. The CEO of the London Stock Exchange, Xavier Rolet, was with her for the effort.

Her office said she "set out the sort of depth of expertise that there is in London and the UK in terms of financial services," as well as "the depth of investment opportunities that there are in the UK."

The Aramco listing is gearing up to be the biggest flotation ever, with Saudi officials valuing the company at more than $2 trillion.

The flotation is part of a broad effort to raise Saudi Arabia's profile and boost government revenues after a sharp drop in oil prices hindered its ability to pay for large infrastructure projects and subsidies that citizens have come to rely on.

Saudi Arabia also spends heavily on defense, ranking as the world's third largest military spender, with billions of dollars in purchases from U.K. manufacturers.

Saudi Arabia is Britain's largest Mideast trading partner, with British exports of goods and services to the kingdom topping 6.5 billion pounds ($8.1 billion) in 2015.

The U.K.-based Campaign Against Arms Trade says the British government has licensed over 3.3 billion pounds ($4.1 billion) worth of arms to Saudi Arabia since March 2015, when Saudi Arabia began a bombing campaign in neighboring Yemen.

A Saud-led coalition has been bombing Iranian-allied rebels known as Houthis in Yemen for two years, but has not been able to seize the capital and other territories under Houthi control.

The U.K. provides the coalition with technical support, precision-guided bombs and intelligence sharing.

Rights groups have called on the U.S., Britain and France to halt the sale of weapons used in the war to Saudi Arabia. The conflict has killed at least 4,770 civilians and wounded more than 8,200 according to the U.N. human rights office.

May discussed the humanitarian crisis in Yemen during her meeting with the Saudi king. Around 21 million people, roughly 82 percent of the population, are in urgent need of humanitarian assistance.

In a gesture to cement the bilateral relationship, the monarch awarded her the Order of King Abdulaziz, named after the founder of Saudi Arabia, Salman's father. Previous leaders who have received the award include her predecessor, David Cameron, and U.S. President Barack Obama.