Size Matters

These days, it seems like everyone is just throwing out ETF's like cinnamon sprinkles. Throw some out there, and see which one sticks. Well, although ETFs are great tools (I've emphasized thsi point in previous articles) to invest in a sector without the risks of company specific problems, don't just choose one based by names.

As of May 1, there were 107 industry-specific ETFs providing exposure to more than 30 different industries, according to a Morgan Stanley report released this week. By design, industry-specific ETFs allow investors to own a basket of stocks in a given slice of the economy.

Initially, two ETFs may appear to be similar by name, but the formulas behind their underlying indexes can result in very different portfolios. Most ETFs are weighted by market capitalization, which means larger companies receive greater representation in the index. But in an equally weighted fund, all stocks carry the same weight, regardless of a company's size, earnings, or revenues (so you'll find more small companies in equally weighted ETFs).

Here's an example of how this plays out. Two retail ETFs: the equally weighted SPDR S&P Retail ETF (symbol XRT), which includes 53 companies, and the Retail HOLDRs Trust (symbol RTH), which has no underlying index and holds just 18 stocks.

Because the S&P fund includes more small companies, it's heavily exposed to apparel--a more cyclical slice of the industry. Companies with market capitalizations of under $5 billion make up 60 percent of the fund, versus just 7 percent in the HOLDRs fund. In that ETF, retail giants Wal-Mart, Home Depot, Target, and Walgreens account for half of the portfolio.

That being the case, do check under the hood with these ETFs. When in doubt, go with the larger names. The bigger companies tend to do better in recoveries, becaue of their size and economy of scale. Plus, at the very least, you've probably heard of Coca Cola or Boeing.

Here's some top picks.

iShares DJ US Oil Equipment & Services (IEZ) holds 55 companies in the Dow Jones Wilshire 2500 Index that are suppliers of equipment or services to oil-field and offshore platform companies.

Market Vectors Global Alternative Energy (GEX): tracks the Ardor Global Index, which includes 30 global companies involved in alternative power production and supporting technologies. The fund will always have 30 percent of assets in non-U.S. companies located in at least three different countries.

PowerShares Water Resources (PHO): tracks the Palisades Water Index, which includes U.S.-listed companies involved in water supply and treatment, and in technologies or services associated with the water industry. At least 80 percent of the index's components must derive at least 50 percent of revenues from water-related activities.