Sales of so-called "smart beta" funds, the fastest-growing segment of the exchange-traded fund (ETF) market, are among the issues that 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 (Finra), is concerned about how varying market environments could affect indices tied to the funds' performance, the regulator said in its annual list of "examination priorities," published on Tuesday. The funds are appearing on Finra's list for the first time this year.

Among other new concerns that Finra will examine this year: firms' marketing practices for a growing number of loan products that allow investors to use their securities as collateral. Investors typically use the loan proceeds to buy second homes, luxury items or pay expenses, Finra said.