DoubleLine Capital's first actively managed exchange-traded fund, the SPDR DoubleLine Total Return Tactical ETF (TOTL), surpassed $500 million in assets in less than three months, according to its administrator on Wednesday.

The SPDR DoubleLine Total Return Tactical ETF, co-managed by widely followed investor Jeffrey Gundlach, had $509.6 million in total assets as of the close on Tuesday, according to State Street Global Advisors, who partnered with DoubleLine to bring the product to market.

"Asset allocators like to have a Gundlach-managed strategy with intraday liquidity," said David Schawel, vice president and portfolio manager of Square 1 Financial. "The ETF gives you fairly diversified exposure to fixed-income through one tradable instrument."

The day-to-day management of the SPDR DoubleLine Total Return Tactical ETF, which started with $112.5 million in assets on February 23, is led by Gundlach, Philip Barach and Jeffrey Sherman.

The SPDR DoubleLine ETF will invest as much as 25 percent in corporate and sovereign high-yield debt, up to 15 percent in securities denominated in foreign currencies, up to 20 percent in non-agency residential mortgage-backed securities, commercial MBS and asset-backed securities and a maximum of 25 percent in emerging markets, according to a filing with the U.S. Securities and Exchange Commission.

Since its launch in late February through May 12, the SPDR DoubleLine ETF has returned 0.04 percent while the Barclays U.S. Aggregate Bond Index has returned negative 0.83 percent.

Intermediate-term bond funds like DoubleLine ETF have faced a challenging bond market. The 10-year Treasury yield has swung 42 basis points from the timeframe low of 1.858 percent on April 1 to the high of 2.281 percent on May 11.

Barach said DoubleLine is managing lower duration and higher yield within the backdrop of good risk management.

"First, the ETF's asset mix differs from the Barclays U.S. Aggregate benchmark," he said. "Second, management seeks to add value through security selection and portfolio construction. In particular, we try to create a portfolio which yields more and has less interest-rate sensitivity than the Barclays Aggregate."