It said $2 billion "will be allocated for investment in a number developmental fields in Egypt, while the other $2 billion will be deposited at the Central Bank of Egypt to support the Egyptian cash reserve".
WAM said the decision was made by Abu Dhabi's crown prince Sheikh Mohammed bin Zayed al-Nahyan who concluded a visit to Egypt on Friday.
"This support comes in the framework of strategic co-operation and co-ordination between the two countries," it said.
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"It also stems from the UAE's firm stand in support of Egypt and its people to promote the reconstruction and development process, as well as in recognition of the pivotal role of Egypt in the region."
The UAE had pledged along with Saudi Arabia and Kuwait a combined $12 billion in aid and investment in March last year to help Egypt's struggling economy.
UAE Prime Minister Mohammed bin Rashid al-Maktoum said at an investment conference in Sharm el-Sheikh at the time that his country's investment includes a $2 billion deposit in the Central Bank, with the rest used to fund projects to be announced later.
The three Gulf countries have channelled billions of dollars to support Egypt since the military ousted Islamist president Mohamed Morsi in 2013.