The findings come from the latest Internationalisation of Food Retailing report, published by CIES and M+M Planet Retail.
The report's author, Gustavo Trompiz, cited Carrefour as a key example.
The giant pulled out of Chile and announced the disposal of EUR1 billion (£689.5 million) of non-core assets during the year, while expanding in China.
The 30 largest retailers, including Wal-Mart, Ahold and Tesco, captured about a third of global retail grocery sales in the year 2003/2004.
These big players continued to consolidate their foreign investments.
Wal-Mart, Carrefour and their rivals will have become 'mega-retailers' by 2010, with the ability to leverage scale across both geographical locations and categories.
Trompiz added: 'We can expect international retailers to invest more in foreign countries and to get increasing returns over time as they master operational, financial, cultural and political issues.'
However, he warned: 'The past year has confirmed that the learning curve is gradual and the risks, such as economic recession, constant. We can expect more adjustments in the short term before the largest food retailers confirm their status as global operators.'