Health care exchange traded funds, particularly those of the biotechnology variety, do not need the help, but these ETFs could another assist if some heavily shorted health care stocks rally into year-end, forcing a wave of short covering.

The health care sector is the best performer in the S&P 500 this year and eight of the top-10 non-leveraged sector ETFs are health care funds. The top five ETFs on that list are the five non-leveraged biotech ETFs, including the First Trust NYSE Arca Biotechnology Index Fund (NYSEArca: FBT), the top-performing sector ETF, and the iShares Nasdaq Biotechnology ETF (NasdaqGM: IBB). [The Dominance of Health Care ETFs in One Chart]

Despite the ongoing bullishness of the health care sector, some of the sectors leaders and glamor stocks are favorite shorts of hedge funds. Short interest expressed as a percentage of Gilead Sciences (NasdaqGS: GILD) float capitalization at the end of October was 3%, or $5.8 billion in dollar terms, according to FactSet data.

Although pharmaceuticals stocks and ETFs have also been stellar performers, short interest at the end of last month for Bristol-Myers Squibb (NYSE: BMY) and Pfizer (NYSE: PFE) was $1.9 billion apiece, according to FactSet. For Johnson & Johnson (NYSE: JNJ) and Eli Lilly (NYSE: LLY) short interest at the end of October was $2.7 billion and $1.8 billion, respectively. Short interest in Merck (NYSE: MRK), like J&J and Pfizer a Dow component, was $1.7 billion, according to FactSet.

Those pharmaceuticals stocks combine for 23% of the PowerShares Dynamic Pharmaceuticals Portfolio (NYSEArca: PJP), one of this year’s top-10 sector ETFs. PJP, which is up 26.2% this year, also features solid biotech exposure, meaning it could benefit from potential short covering of those stocks. [A Fabulous Pharma ETF]

In addition to the aforementioned $5.8 billion short position in Gilead, hedge funds had a combined $4.7 billion short position in Amgen (NasdaqGS: AMGN), Regeneron Pharmaceuticals (NasdaqGS: REGN) and Celgene (NasdaqGS: CELG) at the end of last month, according to FactSet. IBB, the largest biotech ETF, allocates about 32% of its weight to those stocks. FBT, the First Trust biotech ETF, devotes 13.6% of its weight to those stocks.