Vanguard last Friday (1/28/11) introduced the Vanguard Total International Stock ETF (VXUS), which seeks to track the MSCI All Country World ex USA Investable Market Index. The VXUS expense ratio is 0.20%, making it the lowest priced offering in its category.

The snapshot page does not offer much additional information presently, but does show that broad allocations are expected to be 75.3% for Developed Markets and 24.7% for Emerging Markets. The Developed Market exposure by region includes Europe 43.2%, Pacific 24.5%, and North America 7.6%

Vanguard’s prime competitor for VXUS will be another Vanguard ETF. Vanguard FTSE All-World ex-US ETF (VEU) came out nearly four years ago (3/8/2007) and is already the de-facto benchmark of the All-World ex-US category. It currently holds 2269 stocks and has more than $5 billion in assets, while having a slightly higher expense ratio of 0.25%.

This is not the first time that Vanguard has introduced a product very similar to its own existing ones without any explanation. Last September, Vanguard began offering style-box ETFs based on Russell Indexes less than two weeks after launching style-box ETFs based on S&P Indexes. Both came more than four years after Vanguard first offered its original lineup of style-box ETFs based on MSCI Indexes.

Vanguard now has about 29 different ETFs, but they represent just 10 different investment categories. Granted, these 19 additional ETFs are not identical duplicates, but they are similar enough that Vanguard’s shareholders should want to know the difference.

If I didn’t know better, I would think that Vanguard has embarked on strategy of total investor confusion. Perhaps a kinder theory is that Vanguard wants to be index provider-neutral while remaining completely faithful to the broader indexing religion. Whatever it is, I believe Vanguard owes investors an explanation.