In the coming days ahead, short-term swings could make or break the energy sector-related exchange traded fund as short interest on oil stocks rise to a seven-year high.

The Energy Select Sector SPDR Fund (NYSEArca: XLE), which tracks energy companies from the S&P 500 index, has declined 8.6% over the past three months but is slightly up 0.2% year-to-dated. [Oil Sector ETFs Look Cheap as a Long-Term Play]

As of the end of January, the average Energy sector stock had 9.88% of its floating shares sold short, the highest level of short interest for energy stocks since at least 2008, according to Bespoke Investment Group.

The close to double-digit short interest reflects growing concern for the energy sector. To put percentage of short interest in perspective, the only time the markets saw double-digit levels of short interest for any sector was during the global financial crisis.

Short interest reflects the percentage of shares outstanding that investors have sold short but not yet covered or closed out. It provides a gauge of market sentiment, revealing investors’ bearish outlook the market.

However, given the high amount of shorts, a positive turnaround in oil prices could easily fuel a quick rally. For instance, a contrarian investor would benefit from a sudden short squeeze as pessimistic traders rush out of bearish bets if the markets turns bullish.

“By the way, according to our contacts on the Street, there is an inordinate amount of ‘Street Buzz’ going around that there is so much short selling in energy stocks being done by hedge funds that some stocks are becoming hard to borrow,” NYSE floor governor Rich Barry told Business Insider. “It is a hugely crowded trade at the moment.”

West Texas Intermediate crude oil futures rose 4.9% to $51.2 per barrel Thursday while Brent crude oil futures increased 5.0% to $57.4 per barrel. XLE was up 1.2% Thursday. [A Large-Cap Energy ETF to Play the Rebound in Oil]

Energy Select Sector SPDR Fund

For more information on the energy sector, visit our energy category.

Max Chen contributed to this article.