With the example of America Airlines it seems for every 1 share of AAMRQ.DL the person had got them 0.0665 shares of AAL going forward. So for example: 10,000 shares of AAMRQ.DL got you 665 AAL. http://www.fool.com/investing/general/2013/12/11/dont-panic-amr-shareholders-your-investment-is-sti.aspx