PowerShares has been one of the most active issuers of new ETFs this year and no sign of any pause seems to be in sight.

In October, the emerging company (its relatively short history dates back to 2003) introduced another 14 exchange-traded funds (ETFs) on the American Stock Exchange.

The latest offerings build on the company’s traditional expertise. Among the earliest ETFs offered by PowerShares were the Dynamic Market Portfolio (Amex: PWC) and Dynamic OTC Portfolio (Amex: PWO). Both funds, as well as those more recently launched, use an approach dubbed as the “Intellidex” method, which analyzes stocks according to a select set of criteria that include fundamental growth, stock valuation, timeliness and risk factors. This process is conducted quarterly with the goal of capturing an accurate representation of a specific market segment.

According to the prospectus, the new funds have expense ratios of 0.60 percent. Also, all of the funds will have underlying call and put options.

“We are very pleased to be working with the Amex to expand the PowerShares family of ETFs,” says Bruce Bond, president of PowerShares. “The Intellidex stock selection methodology, which uses a sophisticated quantitative methodology to determine the investment merit of a company and whether it should be included in the index, is a cornerstone in our Intelligent ETF business.”

Among the funds launched in October, environmentally friendly approaches seem to be a reoccurring theme. The PowerShares Cleantech Portfolio (Amex: PZD) follows an equally weighted index comprised of 75 publicly traded companies engaged in agriculture and nutrition, air quality, enabling technologies, environmental technologies, materials and nanotechnology, materials recovery and recycling, transportation and logistics, and water purification and management. The idea is to locate companies that improve energy consumption and reduce pollution; all stocks will be selected by Cleantech Capital Indices LLC.

The PowerShares WilderHill Progressive Energy Portfolio (Amex: PUW) follows along similar lines. It’s an equal-weighted index composed of companies engaged in businesses that have the potential to benefit from a societal shift toward various “transitional” energy technologies significant in improving the use of fossil fuels and nuclear power. In this case, Progressive Energy Index is selecting the stocks that comprise the underlying index.

PowerShares Capital Management is an Amvescap company. As of September 29, the firm had $6.4 billion in assets under management in 48 exchange-traded funds.