Biotech Dip Could Be a Buying Opportunity

It's been a rough week for biotech stocks, due to a handful of earnings disappointments and concerns about Amazon's (AMZN) entry into the pharmaceutical sector. As such, the SPDR S&P Biotech ETF (XBI) is pacing for its worst week since late June, while the Health Care Select Sector SPDR Fund (XLV) is set for its worst week in a year. However, if recent history is any indicator, today's biotech weakness could be a buying opportunity. Below, we outline why we're watching XBI and XLV in November, and name one drug stock that could be due for a big bounce.

Biotech stocks have been the best to own in November, with the XBI averaging a gain of 3.84% during the month, going back 10 years -- the best of all exchange-traded funds (ETFs) we track. Further, the fund was positive 70% of the time, according to Schaeffer's Senior Quantitative Analyst Rocky White. XLV, meanwhile, has also ended November higher 70% of the time, racking up an average gain of 1.28%.

After eight straight days of losses, XBI shares were last seen 1.2% higher at $82.76. Another 3.84% surge over the next month would put the ETF just shy of $86 -- and within striking distance of its two-year high, touched Oct. 6. What's more, similar pullbacks have represented buying opportunities on XBI since early 2016, when the ETF began a series of higher highs and lows. More recently, the fund's pullbacks have been contained by its ascending 80-day moving average.

XLV touched a record high of $84.30 just Monday, but has since pulled back to trade at $82.09, down 0.1% on the day. The fund has been making a series of higher highs and lows since the presidential election, ushered higher atop its 80-day trendline, and another 1.28% jump in November would put XLV shares around $83.14.

Should the ETFs rebound in November, a short squeeze could add fuel to the fire. Short interest on XBI represents nearly two weeks' worth of pent-up buying demand, at the fund's average pace of trading. Meanwhile, XLV has roughly a week's worth of short interest on the books.

For speculators looking for an individual biotech stock with potential, Sarepta Therapeutics Inc (NASDAQ:SRPT) could be flashing "buy," if history repeats. SRPT stock notched an annual high of $52.67 last week, but retreated this week, despite the company reporting a smaller-than-expected third-quarter loss and lifting its full-year sales forecast. The security is now within one standard deviation of its 40-day moving average, after a lengthy spell above this trendline, which has been bullish in the past.

After the last eight pullbacks to the 40-day, SRPT shares went on to enjoy an average one-week return of 2.05%, and was higher 75% of the time. One month after pullbacks, the equity was higher 71% of the time, with an average return of 15.72%! A similar rally over the next month would put SRPT stock -- last seen trading around $48.14 -- at $55.70, in territory not charted in over a year.

Sarepta stock could also enjoy a short squeeze. Short interest accounts for nearly 20% of the security's total available float, and would take more than five sessions to repurchase, at SRPT's average pace of trading.