Understand any stock in simple English
Enter a ticker to learn what the company does and how it makes money.
CSL makes medicines from human blood plasma and sells flu vaccines, and it also makes treatments for rare diseases.
CSL is a global medicine maker with two big engines. One collects human blood plasma and turns it into drugs for people with immune disorders, bleeding problems, and other serious conditions. The other, called CSL Seqirus, makes flu vaccines. A third arm, CSL Vifor, sells iron treatments for kidney patients and dialysis care. The company is headquartered in Melbourne, Australia, but it sells in more than 100 countries and earns most of its money overseas, especially in the United States.
The plasma business, CSL Behring, is the heart of the company. Plasma is the yellowish liquid part of blood, and it contains proteins that keep the body working. CSL pays thousands of donors across a network of collection centers, mostly in the US, then runs that plasma through a slow, expensive process to pull out proteins like antibodies and clotting factors. Many of these drugs treat rare diseases with few alternatives. A patient with a bleeding disorder may need treatment for life, and the disease is often serious, so doctors rarely switch brands. That loyalty, plus a short list of companies with plasma expertise, makes the business durable. The main rival is Grifols of Spain, with Takeda also selling plasma drugs. Collecting enough plasma is the constant bottleneck, and CSL spends heavily to open new collection centers and build expensive factories. One of its most famous plasma products is Hizentra, given under the skin at home to people with weak immune systems. Another important line makes clotting factors for hemophilia. Rare disease drugs are rarely cheap. That is partly why CSL is under pressure from health insurers trying to rein in spending on expensive medicines. CSL Seqirus is one of the world's largest flu vaccine makers. It has a special trick: a cell-based vaccine that is grown in cells rather than chicken eggs, which lets it respond faster when a new strain appears. The company also sells an adjuvant, a booster ingredient that stretches a vaccine dose further, which governments stockpile in case of a pandemic. CSL also does a lot with the cash it generates. It pays dividends and recently bought Vifor, the Swiss kidney medicine firm, for about A$17 billion, a bet that iron deficiency treatment could grow alongside its existing kidney and hospital businesses. That deal came with debt and has not yet delivered all the savings promised. In 2025, CSL also ran into trouble: its experimental gene therapy for a rare nerve disease, garadacimab-adjacent research aside, hit a clinical pause, and a slow plasma collection recovery in the US hurt margins. The stock dropped sharply after a 2025 profit warning. That is the tension in this business: selling expensive life-saving drugs to insurers and governments is a wonderful franchise, but it depends on grinding out enough raw plasma, and any wobble in that supply shows up fast in profits.
Saved answer · last researched 19 Oct 2026
see a list of the most recent 300 searches below: