After a few months months in the doldrums, CSL (ASX: CSL) is showing signs it might be about to storm back.

What happened?

The Aussie health giant, which had been dragging under the weight of acquisition doubts and underperforming assets, might have suddenly found momentum.

After tipping a high for 2025 in February with a price per share of a little north of $309, the market has brought it off the boil. Since that high, shares have consistently slipped week-on-week in 2025. The stock closed Wednesday's session at $247.13 a share.

May has been a rollercoaster for CSL shareholders, with a brief rally followed by yet another steady decline, slumping to $234 per share.

But is the bad news now behind CSL investors as the line begins to trend northward again?

Plasma division to the rescue

It turns out one core business unit is currently the engine room for CSL.

“The plasma business is firing on all cylinders,” said Grady Wulff, senior market analyst at Bell Direct on this week's episode of Switzer Investing TV.

“They are seeing volume growth, margin expansion, and they’re also seeing revenues increase because they can increase the price.”

This turnaround is more than just good management. It’s a case of a company leaning into its strengths while other parts of the business falter.

“The reason it’s outperforming is because two of the three main CSL revenue drivers are not performing above market expectations,” Wulff said. “That is CSL Seqirus—so the influenza division—and CSL Vifor, the acquisition.”

What’s not working

CSL Vifor, acquired in 2022 for A$17 billion, was seen as a strategic play to broaden CSL’s portfolio into iron deficiency and nephrology treatments. But so far, it hasn’t lived up to the hype.

“They acquired Vifor a couple of years ago and unfortunately, that has not yet hit the mark,” said Wulff. “It hasn’t delivered the sort of revenue growth the market was hoping for.”

Seqirus, CSL’s flu vaccine business, has also underwhelmed. “The Seqirus division didn’t perform as well in the latest results either,” Wulff noted.

In other words, CSL’s recent gains are not the result of a company firing across all units—but of one star division doing the heavy lifting.

Why the market still loves it

Despite the uneven performance, analysts are warming back up to CSL.

“They’re seeing really good [plasma] donor numbers coming through, which is a leading indicator for revenue,” Wulff explained. “We’re seeing a really strong performance and a beat on expectations.”

That word—beat—is key. The plasma division didn’t just improve; it surprised to the upside. And in this market, surprises are rewarded.

“There’s also confidence that margins can keep expanding, particularly in the US, which is their core plasma collection market,” Wulff added.

Paul Rickard from the Switzer Report was even more direct: “CSL’s the type of company where you don’t worry too much about the short term. You’re backing the quality of the management team and the long-term story.”

What’s next?

CSL is still facing questions over whether Vifor will ever deliver the growth it promised, and whether Seqirus can rebound. But for now, the market seems willing to forgive those weaknesses as long as plasma keeps pulling ahead.

And if all three engines start to fire?

As Wulff put it: “If Vifor and Seqirus get back on track, then CSL’s earnings profile could look materially different—and in a good way.”

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