Ten-year Treasury yields have risen just half a percent over the past month, but a well-known exchange traded fund holding longer-dated Treasurys has been struggling.

The iShares 20+ Year Treasury Bond ETF (NYSEArca: TLT) is off 2.4% over the past month and the chart on the $6.6 billion ETF indicates more weakness could be ahead even though expectation for a Federal Reserve interest rate hike have shifted from June to the late third quarter or fourth quarter.

“TLT had a great 2014 and early part of 2015. TLT hit the top of this steep rising channel a few months ago and stopped on a dime. Now TLT is attempting a breakdown of this channel, where it rallied over 35% in a little over a year,” notes Chris Kimble of Kimble Charting Solutions.

Even with TLT’s recent struggles, investors have poured $180 million into the ETF this month. The aforementioned modest rise in 10-year yields has not stopped investors from allocating $510 million in new money to the iShares 7-10 Year Treasury Bond ETF (NYSEArca: IEF). [Bond ETFs Surprise Investors]

For what it is worth, some traders are still trying to time the top in Treasurys, remaining devoted to ETFs such as the ProShares UltraShort 20+ Year Treasury (NYSEArca: TBT). TBT, which seeks to deliver twice the daily inverse performance of the Barclays Capital US Treasury 20+ Year Treasury Bond Index, has seen April inflows of $51.3 million. [Investors Flee Bond ETFs]