I like the idea of a share index, to give a general feel of the BTC-markets. For your current setup, I would reevaluate the inclusion and/or weight of TAT.ASICMINER, since it is not excluded that that security isn't partially backed by ASICMINER-PT shares, which would cause them to be double-counted.
In general, I would like an index where ASICMINER has less effect on the index, but since this would not be an accurate representation of reality, I don't know if it's a good idea to tamper with the weight-function.
Funds and bonds I would not include. Funds are often baskets of other shares (mixed with some currency), which would cause more double-weighing. Bonds should not fluctuate in price and always trade close to their face value, so they don't serve a purpose in an index. There are the "mining bonds" (that aren't bonds) that are basically inverted difficulty futures and the price of them doesn't necessarily reflect the performance of the market.
Thanks for the input. Double counting could indeed distort the picture and it's obvious when it comes to funds, but it's a bit tricky overall, because even some stocks hold shares sometimes. I remember BASIC holding AM for example. It's probably even worse when it comes to multiple trading plattforms and passthroughs. Another factor are commpany hold shares which are not intended for public trading. Not sure if they should be counted and if not, how to fetch all those data without manual input.
My overall goals:
1. Quantify the amount of money going in and out of the share markets.
2. Follow the flow of money within a market.
My assumption: a sell of one asset leads to a buy of another asset.
Wild example: people are dumping AM, BM and COG to buy ActM shares.