The rules governing the tax-treatment of commodity index-tracking ETN returns are up in the air right now. Barclays' interpretation has been that shareholders pay taxes upon redemption only. However, the IRS is reviewing that treatment.
Barclays Bank promises the return of the index, so investors aren't exposed to the risk that the fund's pre-fee returns will diverge meaningfully from the benchmark's. That's valuable in the commodities space, where it can be difficult to track prevailing indexes given the transaction costs involved.
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