There are many real estate companies worldwide, here are some of the largest ones:

1. CBRE Group: The world's largest commercial real estate services and investment firm based in the United States.

2. JLL (Jones Lang LaSalle): A professional services and investment management company specializing in real estate headquartered in the United States.

3. Colliers International: A global commercial real estate services organization headquartered in Canada.

4. Cushman & Wakefield: A leading global real estate services firm headquartered in the United States.

5. Knight Frank: A global real estate consultancy headquartered in London, United Kingdom.

6. RE/MAX: A global real estate franchise network with more than 100,000 agents operating in over 100 countries.

7. Century 21: A global real estate franchise network with more than 9,000 offices in over 80 countries.

8. Sotheby's International Realty: A luxury real estate brokerage firm with over 23,000 agents in over 1,000 offices worldwide.

9. Coldwell Banker: A global real estate franchise network with over 3,000 offices in 43 countries.

10. Berkshire Hathaway HomeServices: A global real estate brokerage network with over 50,000 agents in the United States and several other countries.