Energy and utilities stocks combine for just 13.75% of the S&P 500’s weight. That is less than the benchmark U.S. index allocates to technology and financial services and barely more than the weight devoted to health care.

However, energy and utilities have been the best-performing sectors in the S&P 500 this year. Whether it is just some profit-taking, sector rotation or a sign of a legitimate flight from these sectors, energy and utilities ETFs are weakening, with the latter showing noticeable signs of increasing technical vulnerability.

The Utilities Select Sector SPDR (NYSEArca: XLU) and the Vanguard Utilities ETF (NYSEArca: VPU) are off an average of 1.7% today, extending their five-day declines to 1.8%. For a good part of July, both ETFs have struggled to stay above their 50-day moving averages. Wednesday’s woes have sent the pair below their 100-day lines.

Those technical issues come amid a backdrop of concern that the defensive utilities sector is richly valued. Earlier this month, Morningstar noted VPU trades at over 100% of its fair value. On Wednesday, five of the six worst-performing sector ETFs are utilities funds. [Utilities ETFs Look Expensive on Valuation]

The Energy Select Sector SPDR (NYSEArca: XLE) is off just 0.4% at this writing, but this year’s top performer of the nine sector SPDR ETFs has shed 2.5% since hitting an all-time high on June 23.

On a technical basis, XLE is not as weak as its utilities counterparts, but the largest energy ETF is trading below its 20-day line and is just 0.7% above its 50-day moving average.