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system
find out the difference between two stocks of the same company (how to identify adrs, etc)
user
generally, when i run across this kind of situation, i look for the investor relations section of the corporate website for a 'stock information' (or similar) tab or link.   this usually contains information explaining the different shares classes, how they relate (if at all), voting and/or dividend rights, and taxation differences for the different classes. however, i have trouble finding such a page on a central byd corporate investor relations page.   i did find this page detailing the hk1211 shares: http://www.byd.com/investor/base_information.html.  i don't know what or why, but something tells me this is an older page. searching on, i also found this page which looks newer and clarifies that the difference you are seeing is between 'a' and 'h' shares. http://www.byd.cn/bydenglish/basic/article.jsp?articleid=1524676.  (i'm guessing but i'd think somewhere in the announcements on this byd.cn site, you may find more details of any structural differences between share classes -- i just didn't want to page through them all.)
assistant