Yields on 10-year U.S. Treasuries are up 3.1% in the past week, but at 2.72%, those yields still have a little way to go before touching the ominous 3% level.

Recent action in utilities ETFs could be a sign that U.S. yields are set to soar again, threatening an array of other income-generating sectors and asset classes such as consumer staples, master limited partnerships and real estate investment trusts. [Utilities ETFs Stung by Rising Rates]

On Monday, there was unusual volume in several U.S. utilities ETFs. For example, the iShares US Utilities ETF (NYSEArca: IDU) saw volume that was well above the daily average on Monday, according to data from ETF execution firm WallachBeth Capital.  [Chart Says Volume Soares in Utilities, Dividend ETFs]

Turnover in the First Trust Utilities AlphaDEX Fund (NYSEArca: FXU) was also unusually high on Monday.  [Volume High Again in Utilities ETFs]

The Utilities Select Sector SPDR (NYSEArca: XLU), the largest utilities ETF by assets, IDU and FXU were three of the worst six non-leveraged ETFs on Monday, according to the WallachBeth data.

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