Sometimes you just have a hunch.

Although there will always be a place for traditional, market cap-weighted ETFs at the core of clients' portfolios, niche ETFs offer intriguing possibilities. These investment vehicles allow you to target a narrowly focused theme or sector, and can add some flavourful sauce to the plain-vanilla main dish.

"[Niche ETFs] are designed for investors who have an active management opinion about a certain subindustry, whether that's a short-term speculative opinion or a long-term, active-management opinion," says Dave Nadig, CEO of ETF.com. "You're making a bet."

In recent years, a seemingly endless variety of niche ETFs have been launched as asset-management firms search for the next big theme that will capture the imagination of investors, says Tyler Mordy, president and chief investment officer at Forstrong Global Asset Management Inc. in Kelowna, B.C. "First mover advantage in the [ETF] industry is huge. There's a race to try to find the next really good play."

Although exotic ETFs aren't right for everyone, these investments give clients an opportunity to express a conviction, as well as the possibility of earning above-average market returns.

Here are seven niche ETFs that might tickle your fancy:

- Spirited Funds/ETFMG Whiskey & Spirits ETF (NYSE Arca: WSKY) Skip the suds and treat yourself to the good stuff. WSKY, launched in October 2016, invests primarily in firms that are engaged in the production, distillation, storage or aging of whiskey. Spirited Funds LLC and ETF Managers Group (both U.S.-based and the ETF's co-sponsors) state that WSKY gives investors the chance to participate "in the potential profits of an industry popularly known for its consistent demand amid varying market conditions and cycles."

- SPDR SSGA Gender Diversity Index ETF (NYSE Arca: SHE) The portfolio managers of SHE, launched in March 2016, evaluate U.S. large-cap firms based on the ratio of women on the board of directors and in executive positions (only senior vice president or higher, thanks). Those firms in the top decile in each sector are included in the ETF's portfolio as long as they have women CEOs or at least one woman on their boards. Holdings are market-weighted. SHE's sponsor, State Street Bank and Trust Co., argues that gender diversity "can lead to better decisions, greater innovation and, potentially, stronger business results."

- Obesity ETF (Nasdaq: SLIM) Like an annoying friend who jogs, SLIM suggests you put down the curly fries and pick up a rice cake instead by investing in firms that stand to benefit from the global fight against obesity. According to U.S.-based Janus Capital Management LLC, which launched Obesity ETF in June 2016: "As obesity and overweight levels rise, so do the enormous direct and indirect medical expenditures for treatment and prevention, which globally are estimated at US$2 trillion annually." Obesity ETF invests in biotechnology, pharmaceutical, health care and medical-device firms for which the business is focused on obesity and obesity-related diseases, as well as in companies that provide weight-loss programs and related supplements.

- WeatherStorm Forensic Accounting Long-Short ETF (Nasdaq: FLAG) If this investment vehicle were a TV program, it'd be called CSI: Special Accountants Unit. FLAG, launched in 2013 by U.S.-based Exchange Traded Concepts LLC, uses financial statement analysis to identify large-cap U.S.-based firms with aggressive revenue recognition in the stock price, then shorts these "red flag" stocks. The ETF also takes long positions in reasonably valued U.S.-based large-caps that have a financial statement suggesting the firm has sustainable revenue, cash flow and earnings.

- Long-Term Care ETF (Nasdaq: OLD) Another niche fund launched last year by Janus Capital Management, OLD is a play on the global demographic trend of increasing longevity. The ETF invests in global firms that are positioned to benefit from providing care to an aging population, including companies that own or operate seniors' living facilities, nursing services, specialty hospitals and seniors' housing; biotech companies for age-related illnesses; and firms that sell products and services to ongoing-care facilities.

- First Trust Cloud Computing ETF (Nasdaq: SKYY) This fund, launched in 2011 by U.S.-based First Trust Advisors LP, flies off into the wild blue yonder by investing in companies actively involved in the cloud-computing industry. SKYY invests both in "pure play" firms directly involved in cloud computing and in non-pure play firms that provide services to the cloud-computing industry as a part of their business. Large-cap tech firms with indirect ties to cloud computing make up 10% of the portfolio.

- PowerShares Chinese Yuan Dim Sum Bond ETF (NYSE Arca: DSUM) This ETF, unveiled in 2011 by U.S.-based Invesco Ltd., invests in government and corporate bonds denominated in renminbi and issued in Hong Kong. DSUM invests in bonds that can range from investment-grade to non-rated, and the ETF doesn't employ currency-hedging strategies. DSUM is a unique ETF, but doesn't fit strictly into the niche or exotic category, Mordy says. DSUM offers investors a chance to participate in an important trend: the internationalization of the yuan. "The longer-term narrative is one of China rising as an economic and a financial power," Mordy adds.

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