The deal between the world's top two brewers, aimed at tapping growth across Africa, highlights the insular nature of Japan's beer makers, which often rely on gimmicks such as seasonal packaging and limited-edition drinks to stimulate a flagging domestic market.
Analysts said more overseas M&A deals could help Japanese brewers broaden sales channels of their existing beer brands.
Forays abroad, such as Kirin's $560 million investment in Myanmar's top brewer in August and Suntory's $16 billion acquisition of U.S. spirits maker Beam Inc in 2014, are increasingly crucial with domestic beer consumption falling in Japan over the past two decades.
Beer sales in January through September fell 0.6 percent in Japan, data this week showed, to a record low and are set for their 19th straight year of decline.
Bankers have already discussed possible deals with Japanese brewers, with Asahi and Suntory showing particularly strong interest, said the people, who declined to be named because they were not authorized to talk to media on the matter.
One person said that Asahi was interested in acquiring European soft drink brands. Asahi and Kirin declined to comment.
A spokesman for Suntory said "the competitive landscape has changed...promoting further M&A," while not commenting directly on its own plans.
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Most of the assets to be sold by AB InBev and SABMiller are expected to be in the United States and China. While the fast-growing consumer markets in Southeast Asia are often seen as the most attractive to Japanese brewers, they are also interested in the U.S. and China, according to analysts.
"It wouldn't just be about buying a brand, but more about acquiring a sales network," said Satoshi Fujiwara, an analyst at Nomura Securities. "Japanese companies already sell their beer in the U.S. but in limited places such as Japanese restaurants."
But he said any asset sale could be competitive, meaning Japanese brewers may not necessarily be winning bidders. Some said Kirin may be cautious, as it was still struggling to turn a profit on its 2011 deal for a controlling stake in Brazil's Schincariol, worth around $2.6 billion at the time.
So far, Australia is one of the few foreign markets where a Japanese brewer has gained a significant footing, with Kirin the second biggest player in the market. With SABMiller and AB InBev occupying the top and third spots respectively, Kirin may find the competition gets tougher.
Australia's regulators could help them out though, with lawyers saying the country's antitrust watchdog may consider blocking the deal there.
Some analysts said that regardless of any deals, the mega-merger could encourage Japanese brewers to boost their comparatively-low shareholder returns to fend off takeover pressure.
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It will "force them to beef up corporate value to stave off the increased risk of takeover, a development which will work in favor of investors," said SMBC Nikko's Okihira.
Return on equity for Japanese beer makers is less than 10 times expected earnings compared with multiples of above 15 for top global beer firms.