World Bank President Jim Yong Kim has made the surprise announcement that he is stepping down after six years in the post.
No reason was given for his unexpected resignation, which will take effect from 1 February.
Mr Kim, 59, was not due to leave until 2022 after he was re-elected for a second five-year term in 2017.
He will "join a firm and focus on increasing infrastructure investments in developing countries", the World Bank said.
"It has been a great honour to serve as President of this remarkable institution, full of passionate individuals dedicated to the mission of ending extreme poverty in our lifetime," Mr Kim said in a statement.
No reason was given for his unexpected resignation.
World Bank chief executive officer Kristalina Georgieva will assume the role of interim president.
The World Bank has a remit to support international development projects. Formed in 1947 to help rebuild European countries devastated by World War II, it supports infrastructure projects with traditional loans, interest-free credits, and grants.
Mr Kim - who was born in Seoul, South Korea - trained as medical doctor before rising through the ranks at the Bank. He was nominated by former president Barack Obama for both his first and second term at the head of the World Bank.
Traditionally, the president of the World Bank has been nominated by the US, while the head of its sister institution, the International Monetary Fund has been picked by European countries. However, when Mr Kim was first appointed in 2012, there was growing pressure from countries in the southern hemisphere for a candidate from an emerging market country to be chosen.
Positioned at 41 in Forbes' Power People 2018 list, he has presided over the dispersal of billions of dollars of World Bank funding. In 2018, the institution made financial commitments worth $67 billion.
Mr Kim has avoided public clashes with US President Donald Trump, but his policy approach was sometimes at odds with the president's approach to climate change.
Under Mr Kim, the World Bank has ended its support of coal power projects - in contrast to Mr Trump's promise to revive the US coal industry.
However in April, Mr Kim bowed to pressure from the Trump administration over loan payments to China. The World Bank agreed to change its lending structure in order to secure a $13b capital increase.
Formed in 1947 to help rebuild European countries devastated by World War II, the World Bank supports infrastructure projects with traditional loans, interest-free credits, and grants.