It is fair to say that CSL Ltd (ASX: CSL) shares had a brutal 2025.
Over the course of the 12 months, the biotherapeutics giant's shares crashed 39% to end the period at $172.65.
For a company long regarded as one of the ASX's highest-quality blue chips, that kind of pullback naturally left investors asking what went wrong.
The short answer is that several headwinds hit at the same time, exposing just how sensitive even elite businesses can be when growth expectations start to unravel. Here's a breakdown of the key factors behind CSL's sharp sell-off.
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Growth expectations reset lower
One of the biggest drivers of CSL's share price decline was a downgrade to its growth outlook. After years of delivering strong and consistent earnings growth, the company was forced to rein in expectations for the years ahead.
Management cut revenue growth guidance for FY 2026 and trimmed profit growth forecasts, signalling that the next phase of CSL's journey would be slower and more uneven than investors had grown accustomed to. For a stock that had long traded on a premium valuation, that reset hit sentiment hard.
Pressure in the CSL Behring division
CSL's plasma business, CSL Behring, has historically been the engine room of the group. In 2025, however, it ran into problems on multiple fronts.
Demand for albumin in China weakened after government cost-containment measures reduced usage, directly impacting sales. At the same time, margin recovery in the plasma business has taken longer than the market expected and weighed on profitability.
This combination undermined confidence that CSL Behring could quickly return to the high-growth, high-margin profile investors had priced in.
Seqirus complications and vaccine uncertainty
CSL's vaccines business, Seqirus, also played a role in the sell-off. Vaccination rates in the United States declined more sharply than anticipated, and management flagged expectations for further weakness.
That uncertainty led CSL to defer the proposed demerger of Seqirus, which had previously been viewed as a potential value-unlocking event. Instead of providing clarity, the vaccines division became another source of near-term earnings risk, further unsettling investors.
External factors added fuel to the fire
Beyond company-specific issues, CSL also faced broader challenges. Heightened volatility in global healthcare markets, changing US trade and tariff dynamics, and a more cautious outlook for global growth all weighed on sentiment.
Even though favourable currency movements provided some earnings support, they weren't enough to offset the cumulative impact of slower growth, operational complexity, and increased uncertainty.
What's next?
The good news is that many analysts believe that CSL shares are starting 2026 in bargain territory.
For example, Morgan Stanley has an overweight rating and $256.00 price target and Morgans has a buy rating and $249.51 price target. These prices targets imply potential upside of 45%+ over the next 12 months.
