You better check your statistics. BHP is an ADR of two BHP.AX shares. RTP is and ADR of four shares of RIO.L. Yahoo probably gives only the BHP and RTP ADR numbers, or only half of the Dual Listed Companies, not for the Groups as a whole.
For example, BHP Billiton Group had 5.6 billion shares outstanding (BHP.AX + BLT.L) mostly in Australia and UK. Check the London and Sydney stock exchanges and the Groups' websites and annual reports for the real numbers. Each Group is owned about 60& by institutions in their home countries (not USA).
Your point is correctimo! I think you meant that RTP is the ADR for Rio Tinto,plc the London based "half" of the dual Listed entity of Rio Tinto. Rio Tinto, Limited is the Aussie,(Melbourne) based "half" of the Group with the ADR RIO.L.
Total # of O/S shares of the Dual Listed Rio Tinto Group per the Notes to their 12-31-08 Financial Statements, diluted, was ~1.290B shares. Of course there was that rights issue during 2009 about the time they backed away from the Chinalco deal that might weigh in on the O/S shares # now.
Rio Tinto is dual listed just as is BHP Billiton is. BHP,plc,(London)shares are "BBL" ADR's here in the U.S, with many less O/S shares by itself than BHP,Limited -(AX), (Australia) whose ADR's here are simply "BHP". This board. Two Aussie shares = one BHP ADR. There are way many more Aussie shares O/S than London shares with the Group, BHP Billiton.
I see some of the fellow's reasoning,(screen name not visible now) but I like the liquidity, solvency, Mgt. diversification of the larger market cap. co. The good old Broken Hills Proprietary Company!
You are right, He SHOULD be careful in comparing the two. I was just trying to add a little clarity, and, of course some of this is JMHO.