Sales of "smart beta" funds, the fastest-growing segment of the exchange-traded fund market, are among the issues Wall Street's private watchdog will review in its 2015 examinations of U.S. brokerages, the regulator said on Tuesday.

The Financial Industry Regulatory Authority is concerned about how market swings affect indices tied to the funds' performance, the regulator, known as FINRA, said in its annual list of "examination priorities." FINRA routinely examines the industry's more than 4,100 securities firms to gauge their compliance with securities industry rules.

Smart beta funds, which are sold as index funds but are actively traded portfolios that can often fail to deliver the outsized returns their issuers promote, are making their debut on FINRA's annual list.

Over the last one- and three-year periods, they have on average lagged their plain-vanilla counterparts in almost every highly competitive category, according to an analysis performed for Reuters by ETF.com, a research firm. Yet they pulling in 60 cents of every dollar flowing to ETFs over the last two years, according to Morningstar.

FINRA's focus on these funds comes as investors reach for products that promise higher returns in a low interest rate environment, said Richard Ketchum, the regulator's chairman and chief executive.

FINRA will also continue to look at the industry's practices involving other risky, high-yield products, including privately issued securities and non-traded real estate investment trusts.

The regulator, for the first time, is looking at a growing number of loan products offered by brokerages that require investors to put their securities up as collateral. Investors typically use the loan proceeds to buy second homes, luxury items or pay expenses.

The exam priorities list also covers many of the regulator's ongoing concerns, such as firms' cybersecurity practices and abusive trading algorithms that can manipulate financial markets and high frequency trading.

FINRA continues to observe shortcomings in several areas at brokerages, including supervision and not putting customers' interests first, it said. The identities of the firms involved were unclear.