At the end of November there were 1,376 exchange traded funds and notes listed on U.S. exchanges, up from 1,093 a year earlier. Many of the ETFs listed over the past year are designed to track popular investment themes such as bonds, dividends and conservative, low-volatility approaches.

New ETFs, designed to appeal to buy-and-hold investors, include strategies that will help stave off market volatility and provide exposure to solid dividend-payers, reports Mark Jewell for MSN Money. Many fund providers are moving away from the tried-and-true passive ETF formulas and are beginning to dabble in alternative strategies, such as screening for stocks with the lowest-volatility or highest dividend providers. [New Factor-Based ETFs from Russell]

Current popular ETF investment styles include reduced volatility, dividend-income payers and bonds. [Dividend ETF Gets Warm Reception in Europe]

Ryan Issakainen, ETF strategist with First Trust, points out that ETFs are now starting to deliver β€œan investment strategy, rather than just replicating a benchmark.”

Most ETFs are like index mutual funds in that they hold a basket of securities and attempt to match market movements, except ETFs are cheaper since there is no need to pay a manager to pick stocks. Additionally, ETFs may be easily traded during the day.

The three largest ETF fund providers are iShares, State Street Global Advisors and Vanguard. [What are ETFs? β€” Surveying the Landscape]

PowerShares S&P 500 Low Volatility Portfolio (NYSEArca: SPLV)

For more information on ETFs, visit our ETF 101 category.

Max Chen contributed to this article.