Why did CSL shares just crash 17%?

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CSL Ltd (ASX: CSL) shares are being hammered once again on Tuesday.
In morning trade, the biotech giant’s shares are down a disappointing 17% to a new 52-week low of $176.23.
Why are CSL shares crashing again?
Investors have been rushing to the exits this morning after the embattled biotech leader released an update ahead of its annual general meeting.
According to the release, the company has downgraded its guidance for FY 2026 just a little over two months after first providing it to the market.
In August, CSL was guiding to revenue growth of 4% to 5% in FY 2026 in constant currency.
In addition, it advised that its net profit after tax before amortisation (NPATA) excluding non-recurring restructuring costs was expected to be in the range of approximately US$3.45 billion to US$3.55 billion in constant currency. This represented annual growth of approximately 7% to 10%.
CSL has also spoken previously about targeting double-digit annual profit growth over the medium term.
Downgraded guidance
Today’s update reveals that while the majority of the business is performing well, it is seeing two factors that will impact its results in the first half of FY 2026.
The first is it has seen a greater decline in influenza vaccination rates in the U.S. than expected. The other is the impact of government cost containment measures in China reducing demand for albumin.
In response to these challenges, management has downgraded its revenue growth guidance to 2% to 3% and its NPATA growth guidance to 4% to 7%.
And looking ahead, it believes the ongoing uncertainty in the U.S. influenza vaccine market will restrict its NPATA growth to the “high single digits” for FY 2027 and FY 2028.
Commenting on the downgrade, CSL’s CEO, Dr Paul McKenzie, said:
In our Seqirus business, we have seen a greater decline in influenza vaccination rates in the U.S. than we expected. This is despite a positive recommendation from the U.S. administration on influenza vaccines and an unprecedented level of infection impacting public health.
This challenge impacts our forecasts, resulting in overall Seqirus revenue for Financial Year 2026 declining by mid-teens, versus our previous outlook of revenue declining by high single digit.
One small positive is that Dr McKenzie does see scope for a return to double digit profit growth in FY 2027. However, it would require a big turnaround in vaccination rates. He said:
Due to ongoing uncertainty in the U.S. influenza vaccine market, while there are some scenarios in which group NPATA growth may touch double digits, we believe high single-digit growth is a more appropriate expectation until the U.S. influenza vaccine market improves.
Demerger delayed
In other news, CSL has revealed that it will be pushing back the planned demerger of its CSL Seqirus business until market conditions improve. It said:
Our priority is to maximise shareholder value. Given the heightened volatility in the current US influenza vaccine market, we have concluded that advancing with the previously proposed demerger timing will not fully capture Seqirus’ value potential




