CSL Ltd (ASX: CSL) and Telix Pharmaceuticals Ltd (ASX: TLX) have both fallen a long way from their highs.
That has made two very different biotech shares much more interesting to me.
I like the long-term potential of both companies, but which one would I buy today?
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Why I like CSL shares
CSL has spent decades building capabilities across plasma-derived therapies, vaccines, iron deficiency, and other specialist areas of medicine.
Its plasma business is particularly difficult to recreate. The company needs collection centres, manufacturing facilities, regulatory approvals, medical expertise, and relationships with healthcare providers around the world.
I think that scale gives CSL a strong foundation for recovery.
The company has faced a difficult period, and confidence has taken a hit. However, many patients depend on its therapies for serious and complex conditions, giving CSL exposure to healthcare needs that should continue growing over time.
At around $123.06, the valuation really catches my attention.
According to CommSec consensus estimates, CSL is forecast to generate earnings per share of $8.20 in FY26 and $8.34 in FY27. That places the shares on forward price-to-earnings ratios of approximately 15 times and 14.8 times, respectively.
Those multiples look attractive to me for a global biotechnology company with CSL's market positions and earnings base.
Forecast dividends of $3.64 and $3.79 per share imply yields of around 3% and 3.1%, which is a welcome addition.
Why Telix interests me
Telix is building a radiopharmaceutical business focused on using targeted radiation to find and potentially treat cancer.
Its commercial imaging products give doctors another way to identify prostate cancer, while the company is developing products across other cancers and rare diseases.
I find that opportunity exciting. Better imaging could help doctors see where disease is located and choose treatment more accurately, while successful therapeutic products could open a much larger market.
Telix also has commercial revenue today, which separates it from some biotechnology companies relying entirely on future clinical success.
However, investors are being asked to accept more uncertainty. At $14.21, Telix trades on approximately 233 times forecast FY26 earnings and 273 times FY27 earnings. The valuation falls to around 57 times FY28 earnings based on expected earnings per share of 25.1 cents.
That sharp improvement depends on successful launches, regulatory progress, clinical development, and continued investment in its commercial network.
No dividends are expected across the forecast period, which is understandable for a company still putting substantial money into growth.
Which would I buy?
I would choose CSL shares.
Telix may offer greater upside if its pipeline delivers, and I would be happy to own the shares as a higher-risk growth investment.
CSL gives me more confidence at its current valuation. It already has global scale, established products, and earnings that support a much lower valuation than Telix.
I also think the market has become too pessimistic about CSL's ability to recover.
Foolish takeaway
Both ASX shares could be considerably more valuable in a decade, although they offer very different journeys.
Telix is the more speculative choice, with exciting technology and several ways for the business to expand. CSL provides a larger and more established healthcare operation at a valuation I find difficult to ignore.
At today's prices, I think CSL offers the stronger balance between upside and risk. That makes it my preferred buy.
