According to Bloomberg, 3 companies control about 80% of the WORLD's seaborn (exported) IRON ORE marketshare.
These companies are (in order of marketshare):
1. Brazil's Vale (RIO...$163 Billion marketcap) - WORLD's LARGEST producer
2. England's Rio Tinto (RTP...$162 Billion mCap) and
3. Australia's BHP Billiton (BHP...$223 Billion marketcap)
FYI, Iron ore is an essential input/raw material for producing STEEL. According to Wikipedia, 98% of all mined iron ore is used to create steel.
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Anecdotally, No wonder China and India (ArecelorMittal Steel - MT) are concerned about a potential merger between mining giants BHP and RTP...can you say PRICING POWER !!
Lastly, for lists of the World's Largest Steel Producers (countries + companies), please refer to my archived 4/05/08 posts titled 'REF - World's Largest Steel Producers' and 'REF - World's Largest Steel Producing Companies'.
bloomberg.com/apps/news?pid=conewsstory&refer=conews&tkr=MT:US&sid=akBEPNWVyi7o
Data Courtesy: Bloomberg + Wikipedia
Full Disclosure: I own shares of MT.+ Wikipedia