(Bloomberg) --  The $4.3 billion iShares 20+ Year Treasury Bond ETF saw investors withdraw $1.7 billion of cash in the six weeks ended June 5. That was nearly 30% of its market capitalization, and the worst six-week string of outflows since its 2002 inception. The exodus left it with a net $1.8 billion of outflows so far this year, the most of any bond fund, according to Bloomberg data.

“It’s going along with the overall Treasury market,” said Aaron Kehoe, managing director of fixed-income operations for Cantor Fitzgerald LP’s ETF business in New York. “You’ve had a decent selloff in the past few weeks.”

Subscribe Now

Access to premium content including in-depth coverage of mutual funds, hedge funds, 401(K)s, 529 plans, and more.

3-Week Free Trial

Insight and analysis into the management, marketing, operations and technology of the asset management industry.