Overall closed-end fund (CEF) usage has increased significantly since 2013, according to a study focused on financial advisers and their use of CEFs released by Nuveen, the investment management arm of TIAA.

Nearly two-thirds of advisers (62%) currently use CEFs in client portfolios—up from roughly half (51%) in 2013. Closed-end funds remain an attractive investment option as financial advisers are reportedly recommending the funds to clients seeking income and diversification opportunities for income portfolios.

“Income investors have been on the hunt for yield for years,” says Anne Kritzmire, managing director of closed-end funds at Nuveen. “Many of these investors and their advisers are finding that closed-end funds can fulfill their need for both income potential and the opportunity to receive cash flow from non-traditional or less liquid strategies, such as alternatives or real assets.”

Of those advisers who reported increasing CEF usage over the past year, the top two reasons include the attractive yield and return on investment as well as helping clients generate more income in their portfolios.

Overall, income producing investments remain in high demand, with nine out of 10 advisers (91%) saying clients ask about income producing investments—such as CEFs and other fund types. Increasing income remains the top reason for using CEFs in investment portfolios, according to 62% of the financial advisers surveyed who use CEFs. When looking for new sources of income, more than half (57%) of all advisers recommend CEFs as an investment option.

The study, also conducted in 2013 and 2016 by Dubick & Associates, included a weighted statistically valid sample of 326 financial advisers from wirehouses, regional broker/dealers, independent broker/dealers, registered investment advisers, bank and insurance companies. The 2017 study was fielded from April 27 to May 11.