The Health Care Select Sector SPDR (NYSEArca: XLV) is this year’s top performer among the nine sector SPDR exchange traded funds and the race is not even close.

XLV, the largest healthcare ETF by assets, is up 10% year-to-date, an advantage of more than 300 basis points over the Consumer Discretionary Select Sector SPDR (NYSEArca: XLY) and better than double the returns offered by the Materials Select Sector SPDR (NYSEArca: XLB).

Up 2.3% over the past month, XLV resides just pennies below its all-time set in March. Superlatives like that might imply XLV and the broader healthcare sector over-extended and ready for a pullback. In reality, the ETF is primed for a breakout that could leave the old highs in the dust. [Behind the Stellar run for Healthcare ETFs]

“Can this hot performance continue? Check out the pattern XLV has been forming the past few months,” advises Chris Kimble of Kimble Charting Solutions. “Over the past 90-days, XLV remains at the top spot as well, up a little over 2%. XLV could be forming a bullish ascending triangle, as it looks to have nearly a flat top and rising bottoms. Two-thirds of the time this pattern leads to higher prices.”

In the near-term, favorable seasonality for biotechnology stocks could boost XLV. The Memorial Day through Labor Day period is usually kind to biotech stocks. The $14.3 billion XLV allocates 20.4% of its weight to the biotech industry, its second-largest industry behind 42.7% to pharmaceuticals. Gilead Sciences (NasdaqGS: GILD) and Amgen (NasdaqGS: AMGN) are the biotech names found among XLV’s top 10 holdings. Those stocks combine for over 10% of the ETF’s weight. [Biotech ETFs not out for Summer]

From May through the end of August, XLV, on a historical basis, only ranks as one of two best sector SPDRs, on one occasion: In June. Even in that case, XLV being the second-best in June means it is just less bad than its sector counterparts because, dating back to 1999, XLV’s usually posts a modest June loss, according to CXO Advisory.

“The key for XLV at this time is for it to break above the nearly horizontal resistance line. Should it breakout and the pattern read be correct, the measure move would suggest that XLV could push 10% higher quickly,” adds Kimble.