One of our favorite and most useful resources for data on Exchange Traded Products comes from the ETF Industry Association (etf-ia.com). Each month they publish a report summarizing trends in the exchange traded industry regarding assets under management (AUM) and net cash flow, among other things. You can be added to their email list to receive the monthly newsletter, by clicking here. You are also able to export this data to Excel, or subscribe to access even more extensive stats. Below is their summary of the trading activity in the ETF industry for July:

• Assets in US listed Exchange Traded Funds (ETF) and Exchange Traded Notes (ETN) totaled approximately $1.21 trillion at July 2012 month-end, an increase of 9% over July 2011 month-end, when assets totaled $1.11 trillion.

• ETF/ETN net cash inflows totaled approximately $17.1 billion for the month of July 2012, bringing year-to-date 2012 net cash inflows to $93.0 billion.

• At July 2012 month-end, there were 1,486 U.S. listed products, an increase of 15% compared to 1,295 U.S. listed products at the same time last year.

• Equities led all categories for July with $17.1 billion in net inflows.