State Street Global Advisors, a Boston-based asset manager, and DoubleLine Capital have launched two new exchange-traded funds designed to combat an uncertain bond market, the firm announced.

The SPDR DoubleLine Short Duration Total Return Tactical ETF (STOT) and the SPDR DoubleLine Emerging Markets Fixed Income ETF (EMTL) began trading on the Bats Global Markets stock exchange on Thursday.

Developed by State Street and DoubleLine Capital, the new ETFs build on the success of the SPDR DoubleLine Total Return Tactical ETF (TOTL), State Street says.

“Our clients have been asking us for solutions to help them navigate ongoing bond market uncertainty,” says James Ross, executive vice president and global head of SPDR Exchange Traded Funds at State Street. “We’re pleased to be expanding our relationship with DoubleLine to seek to help clients address this challenge. These additions to the SPDR lineup provide investors with new actively managed fixed-income ETFs that may be able to help strengthen and complement core bond holdings.”

The SPDR DoubleLine Short Duration Total Return Tactical ETF seeks to maximize current income with a dollar-weighted average effective duration between one and three years. The fund is managed by Jeffrey Gundlach, chief executive officer and chief investment officer of DoubleLine Capital; Philip Barach, DoubleLine’s president; and portfolio manager Jeffrey Sherman, State Street says.

The SPDR DoubleLine Emerging Markets Fixed Income ETF is designed to provide high total return from current income and capital appreciation. The fund is managed by Luz Padilla, director of DoubleLine’s International Markets Fixed Income Team, Mark Christensen and Su Fei Koo. The fund seeks to maintain a weighted average effective duration between two and eight years through active security selection that combines bottom-up research with sovereign macro overlays, according to State Street.