The two brewers said the UK's Takeover Panel had extended the deadline by which AB Inbev must make a firm offer for SABMiller until 1700 on November 11.
On October 28, the pair secured an extension of the deadline until 1700 today, saying they needed more time for talks.
A statement from the companies said: "Since that announcement, SABMiller and AB InBev have made good progress in agreeing the terms of the possible offer which will be set out in detail in any announcement of a firm intention to make an offer."
Stella Artois brewer AB Inbev also makes Budweiser, Corona and Leffe, while Britain-based SABMiller - which holds second position - owns Peroni, Grolsch and Pilsner Urquell beers.
ABI employs about 1,000 people at its UK breweries in Magor, Samlesbury and Mortlake, as well as its company headquarters in Luton. It has at least 200 beer brands.
SABMiller has around 69,000 staff in more than 80 countries, from Australia, Zambia and Colombia to the Czech Republic, South Africa and the US, also producing more than 200 beers.
Formerly known as South African Breweries, SAB acquired US rival Miller Brewing Company in 2002, resulting in the renaming of the group as SABMiller.
A merged group would be worth about £177bn and would add AB InBev's dominance of Latin America to SABMiller's strong presence in Africa, as well as their breweries in Asia.