not sure about pure beta sounds like a marketing term, but etn's have a different structure than etf's and are debt instruments. You have to be careful with anything labeled etn:
http://wiserinvestor.com/etfs-vs-etns-you-better-be-careful/
ETNs are debt instruments. Debt instruments do not own anything but a promise to track an index. The largest ETN based on assets is Barclay’s iPath
Dow Jones Commodity Index (
DJP). From iPath’s website, we see DJP’s largest holdings are 30% energy, 21% grains, 19% industrial metals, 12% precious metals, 2% livestock and 16% other. At first glance, it would appear that you own commodities with this allocation. However, this allocation is used only as a measure for performance. An investor does not own any commodities, only a promise from
Barclays to pay an investor the theoretical allocation of the commodity index. If an ETN provider should go bankrupt, the investor will not receive his or her investment back. Why?
Because an ETN is considered an unsecured debt instrument.
An example of this is the recent
Lehman Brothers failed ETNs. The three ETNs were Opta Lehman Commodity, Agriculture and Private Equity. In September 2008, these ETNs halted trading when Lehman Brothers failed. Currently, the final results are being sorted out, but it appears that Lehman ETN holders will receive 2 cents on the dollar from their original investment. Shortly after Lehman’s collapse, Bear Stearn’s ETN holders were hours from the same fate, when
JP Morgan stepped in an purchased the company.
http://www.etftrends.com/2009/06/7-differences-between-etfs-etns/