Deloitte has released a report on the global powers of retail in 2010. The report lists top 250 retailers in the world based on their 2008 figures. According to this report the top 10 players in global retail arena are these:

1- Wal-Mart - US
2- Carrefour - France
3- Metro - Germany
4- Tesco - UK
5- Schwarz - Germany
6- Kroger - US
7- Home Depot - US
8- Costco - US
9- Aldi - Germany
10- Target - US

You can access the report from this link.