ADIC will become part of the Mubadala group, with a combined portfolio worth over $200 billion, a source familiar with the deal told Reuters.
United Arab Emirates state news agency WAM said ADIC's board would now report to Mubadala's board, with Eissa al-Suwaidi remaining executive director of ADIC. It did not give details of how the funds' strategy might change under the new arrangement.
ADIC started operating in 2007 and is responsible for investing worldwide part of the Abu Dhabi government's surplus financial resources, earned from oil exports.
Mubadala, itself formed by a merger last year involving another Abu Dhabi fund, International Petroleum Investment Co, had assets worth 465.5 billion dirhams ($126.8 billion) at the end of last June and made a net profit of 4.2 billion dirhams in the first half of 2017.
Abu Dhabi, the richest of the seven emirates that form the UAE, has ridden out the last few years of low oil prices relatively comfortably, but it has been seeking to save money and make many of its assets more efficient by streamlining them or arranging tie-ups.
On Tuesday officials announced that Aldar Properties, Abu Dhabi's top real estate developer which is about 30 percent owned by Mubadala, would form a joint venture with Dubai's Emaar Properties to develop local and international projects worth as much as 30 billion dirhams.
It was not immediately clear whether the ADIC news presaged more mergers or tie-ups for Abu Dhabi funds. The emirate's biggest sovereign fund, Abu Dhabi Investment Authority, has an estimated $828 billion of assets and is the third biggest in the world.