This report discusses what is known about the IPv4 market transfers which have occurred since the implementation of specified transfers within the ARIN, RIPE, and APNIC region. The report brings together a number of sources to come up with the a total of 83 transactions representing 204 blocks for a total of 6 million IPv4 addresses traded between 2009 and the first half of 2012.
The data for IPv4 market transactions is obscured, however, due to the lack of transparency for all transactions. While many have called for additional transparency, full transparency seems unlikely given the current constraints of the RIRs and the lack of other compelling regulations which would require disclosure of IPv4 market transactions.
As expected, the source of most of the transferred blocks are legacy IPv4 holders in the ARIN region. The authors seem surprised that the majority of the transfers occurred in the ARIN region. Given the expected supply for the IPv4 transfer market was expected to come from legacy IPv4 holders (who are largely in the ARIN region) and that an inter-RIR transfer policy was not in place until mid-2012, it is a logical conclusion that the majority of transfers would occur from and to ARIN region entities.
Unfortunately, I believe the study is also laden and interwoven with the authors opinions regarding the market rather than strictly focusing on the facts about the known market.