Why did CSL shares crash 21% in August?

This biotech has a month to forget in August.

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CSL Ltd (ASX: CSL) shares had a month to forget in August.

During the period, the biotechnology giant's shares lost over 21% of their value.

This was driven by the release of the company's full year results. And although CSL delivered a result in line with expectations, its key CSL Behring business underperformed.

Analysts at E&P summarised why investors were so disappointed with the results. They said:

Behring drove the gross profit shortfall in 2H25 and into FY26, with sales more heavily affected than expected by the US Medicare Pt D redesign (-1.9% vs. our -1.0%), and the loss of several ex-US Ig tenders (-3–4% sales impact in FY26). Margins were lower for several reasons, most notably the Medicare Pt D impact which is all margin, and additional investment in headcount for the Rika/i-nomogram rollout. CSL also stepped away from previous Behring GP margin guidance; they still expect to get there, all the levers are still in place, but they are no longer committing to timing (i.e. it's likely been pushed out).

CSL also announced plans to divest its CSL Seqirus business into a standalone ASX listing. It stated:

A demerger will allow autonomy to set an independent strategic direction, including capitalising on potential opportunities that may arise in a highly dynamic vaccines market, as well as reducing complexity, making the business more agile and efficient to manage.

Are CSL shares attractively priced now?

The team at Macquarie Group Ltd (ASX: MQG) remains positive on CSL and its shares despite last month's disappointing results.

Commenting on its post-results selloff, the broker said:

Despite downgrades to earnings, we view today's price movement as an overreaction. Incorporating more conservative FY26 forecasts compared to guidance, we see the current valuation as undemanding (trading at P/E ~20x with ~10% EPS growth). Outperform.

Macquarie now has an outperform rating and $295.90 price target (from $347.50) on its shares. This offers material upside of 40%+ over the next 12 months.

It is also worth noting that E&P remains bullish as well. It has a positive rating on CSL's shares with a trimmed price target of $294.21. It said:

The key question is whether Behring's weak 2H25 signals structural pressure or a temporary setback. Management insists it's the latter, although medium-term Ig growth expectations have effectively eased to mid-to-high single digits (still respectable). At this stage, we retain our view the industry can adjust to manage over-supply risks (i.e. lower collections including 3P). On balance, we see the sell-off as a potential buying opportunity. Retain Positive rating.

Motley Fool contributor James Mickleboro has positions in CSL. The Motley Fool Australia's parent company Motley Fool Holdings Inc. has positions in and has recommended CSL and Macquarie Group. The Motley Fool Australia has positions in and has recommended Macquarie Group. The Motley Fool Australia has recommended CSL. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Scott Phillips.

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