Infrastructure investing and emerging markets investing had been among the hottest asset classes for new investment in recent years, and now, a new index seeks to combine the two under one methodology.

The rhetoric on the potential market for infrastructure investing, particularly in the developing world, has been bandied about quite a bit in the industry and by the press: potentially $20 trillion in the next two decades due to a particular strain and need for infrastructure investment in the emerging economies.

The S-Network Emerging Infrastructure Builders Index (EIBI), launched late last week, and created by S-Network Global Indexes, is notable for its emerging markets twist on infrastructure investing. Beyond that, EIBI also has a specific focus on companies defined as "builders." S-Network breaks down the infrastructure world into two main camps: builders and providers.

Providers are defined as companies that make major up-front investment in infrastructure to profit over the long term, whereas builders maximize income during the building phase of projects. EIBI is branding itself as the first infrastructure "builders" index.

These builders don't all have to be based in the emerging markets, either. EIBI includes 66 stocks in all, but the index also invests in developed market stocks that have extensive infrastructure business in emerging and middle income markets.

Natural Resources 

Another notable aspect of the index is the extent to which natural resource firms are an important subsector. The index covers seven sectors, and among them, Metals/Mining is the only major sector for the index in which companies do not have to be defined as infrastructure builders.

Three of the index top 10 holdings are natural resource companies: Brazil's Vale, Russia's Norilsk Nickel, and China's Jiangxi Copper Company. Overall, EIBI has a 16% weight to the natural resource sector.

PowerShares is planning to launch an exchange-traded fund based on EIBI in mid-October. The ETF will take aim at the two major infrastructure investments: iShares S&P Global Infrastructure (NYSEArca: IGF) and the SPDR/FTSE Macquarie Global Infrastructure Fund (AMEX: GII).

Neither of these existing infrastructure ETFs has the emerging market, or natural resource exposure, directly covered by the S-Network index. However, the natural resource slant is already well represented in the natural resource ETF space.

This might not be an ideal time for a combined infrastructure/emerging market launch: IGF and GII have together amassed less than $250 million through the end of August. IGF is down more than 24% year-to-date, while GII is down 19%, according to Morningstar data through yesterday.

On the other hand, the index and ETF will present a unique slant on important long-term investment trends, and the first-mover advantage has often resulted in an advantage in the ETF space.