Why did the CSL share price tumble in July?

The CSL Limited (ASX: CSL) share price continued its slide in July.

During the month, the biotherapeutics company’s shares lost just over 3% of their value.

This is particularly disappointing given that the S&P/ASX 200 Index (ASX: XJO) rose almost 3% over the same period.

Why did the CSL share price underperform again?

There were a couple of potential reasons for the decline in the CSL share price last month.

The first was weakening investor sentiment following the company’s guidance update the previous month.

Investors were racing to the exits in June after management advised that it is projecting profit growth of ~13% to 18% to the range of ~US$2.9 billion and US$3 billion in constant currency in FY 2024.

This was short of expectations, with the market previously believing that favourable plasma collection tailwinds were going to support margin expansion and drive even stronger growth.

What else?

Also potentially weighing on the CSL share price last month was news that a rival has had great success with a competing therapy.

That rival is Argenx SE (NASDAQ: ARGX), which reported positive topline data from the ADHERE study of Vyvgart Hytrulo in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). CSL’s immunoglobulins are used to treat sufferers of this condition.

In its release, Argenx said:

CIDP is a chronic, progressive autoimmune disease that can cause substantial disability in those affected, often leading to impaired ambulation or difficulty completing normal daily tasks without help. The positive ADHERE data show that Vyvgart Hytrulo may represent a new patient-forward treatment option that can prevent symptom deterioration while minimizing side effects and treatment burden.

The good news is that one leading broker isn’t concerned by the news. UBS feels that the worst-case scenario for CSL from Vyvgart is a ~3% revenue hit. But even then, the broker feels that this is unlikely to be the case.

It’s no wonder then that its analysts feel that this recent weakness has created a buying opportunity. UBS currently has a buy rating and a $340 price target on its shares. This implies an over 25% upside from current levels.