As the biotech group continues to fight back, one of its most recognizable stocks — Biogen (BIIB) — is attempting to break out from a key bullish formation. The stock is up about 25% from its April lows, which doesn’t stand out much given that many other stocks and ETFs are up just as much, if not more. However, over that time, BIIB has been forming a constructive technical base resembling a bullish cup-and-handle formation. In recent days, the stock has been attempting to break out from this pattern. It is also now testing its 200-day moving average, a level it has not traded meaningfully above since 2023. On this chart, holding above the $137 area trigger the breakout and produce an upside target near $164. While BIIB still has a long way to go before getting back to its former highs (near $430), successfully breaking out and holding above this long-term moving average would be an important first step. Lessons from 2024’s failed breakout Even though the stock has been in a persistent downturn for many years, it has staged rally attempts before, often forming bullish patterns like the current one. The last time this occurred was during the spring and summer of 2024, when BIIB formed a very similar cup-and-handle formation and attempted to break out. At that time, the stock was also testing the 200-day moving average, but the breakout never gained traction after numerous failed attempts. When that effort proved unsuccessful, the stock completely unraveled, declining all the way into the lows reached this past April. Needless to say, a stronger follow-through effort is critical this time for a different outcome to occur. Key differences this time There are some key differences this time. First, the stock is finally breaking above a very steep downtrend line that has been in place for the past 10 years. Historically, when BIIB has pushed above similar long-term downtrend lines, it has often given way to powerful upside moves — sometimes lasting only a few weeks, but other times stretching much longer. Second, this is the only rally attempt in recent years occurring from an oversold monthly condition. In other words, the “rubber band” has become extremely stretched to the downside, raising the potential for a sharp snapback rally if momentum continues to build. Long-term oversold In fact, the monthly RSI recently dipped below the 25 level, producing the lowest 14-month RSI reading in Biogen’s history, going back to the early 1990s. As shown here, the stock had not registered an oversold monthly condition since the company’s first few years as a publicly traded entity. The first instance occurred in 1993, followed by another in 1994. Needless to say, the stock eventually leveraged those deeply depressed states to begin an uptrend that lasted more than 30 years. This is not a prediction about the next few decades, but it illustrates that despite being a perennial underperformer for the past 10 years, BIIB may now be in a position to leverage this historic long-term oversold condition. If the stock can also take advantage of the discussed short-term bullish pattern, hold above its 200-day moving average and sustain its break above the long-term downtrend line, the technical complexion could continue to improve in the weeks and months ahead. DISCLOSURES: None. All opinions expressed by the CNBC Pro contributors are solely their opinions and do not reflect the opinions of CNBC, NBC UNIVERSAL, their parent company or affiliates, and may have been previously disseminated by them on television, radio, internet or another medium. THE ABOVE CONTENT IS SUBJECT TO OUR TERMS AND CONDITIONS AND PRIVACY POLICY . THIS CONTENT IS PROVIDED FOR INFORMATIONAL PURPOSES ONLY AND DOES NOT CONSITUTE FINANCIAL, INVESTMENT, TAX OR LEGAL ADVICE OR A RECOMMENDATION TO BUY ANY SECURITY OR OTHER FINANCIAL ASSET. THE CONTENT IS GENERAL IN NATURE AND DOES NOT REFLECT ANY INDIVIDUAL’S UNIQUE PERSONAL CIRCUMSTANCES. THE ABOVE CONTENT MIGHT NOT BE SUITABLE FOR YOUR PARTICULAR CIRCUMSTANCES. BEFORE MAKING ANY FINANCIAL DECISIONS, YOU SHOULD STRONGLY CONSIDER SEEKING ADVICE FROM YOUR OWN FINANCIAL OR INVESTMENT ADVISOR. Click here for the full disclaimer.