Pfizer Inc ( PFE ) shares are on the move Monday after activist Starboard Value acquired a $1 billion stake in the pharmaceutical giant.

What Happened: Activist investor Starboard Value has taken a roughly $1 billion stake in Pfizer and plans to push for changes, according to a Wall Street Journal report.

People familiar with the matter said Starboard has approached former Pfizer executives Ian Read and Frank D'Amelio to help with the turnaround efforts. The former executives are reportedly interested in helping. Read was Pfizer’s CEO from 2010 to 2018, and D’Amelio served as CFO from 2007 to 2021.

Starboard’s specific plans and interactions with the company are unknown, but the activist investor is focused on recent underperformance.

Pfizer shares are down more than 50% since the stock hit an all-time high around $61 in December 2021 after the company was the first to deliver a COVID-19 vaccine. Pfizer shares are also up just 2% year-to-date, while the S&P 500 has gained approximately 21%. Pfizer's ( PFE ) stock is currently trading below where it was when current CEO Albert Bourla took the reins.

BMO Capital Markets analyst Evan Seigerman weighed in on the Starboard news in a new note to clients on Monday. The analyst suggested that Bourla may be in the hot seat as investor frustration mounts.

“With shares down -0.73% YTD (SP500 +21.00%) and no easy path forward, this seems like the ideal story for an Activist,” Seigerman said. “Unfortunately, solving the many woes of PFE will likely take time vs. a quick fix.”

Pfizer has been under pressure from investors to turn things around ever since the drugmaker overestimated the future demand for its COVID-19-related offerings. As the world has returned to normal, Pfizer has battled falling COVID-19 sales, which has led to downbeat guidance and weighed on shares.

Pfizer has struggled to keep up with competitors in the GLP-1 space as its first attempt at a weight-loss pill largely underwhelmed. The report indicates that some analysts have also criticized the company for having a lack of discipline regarding M&A efforts and other aspects of managing the business.

In its most recent quarter, Pfizer said it was continuing to focus on commercial execution, realigning its cost base and setting a foundation for future margin expansion. The second quarter marked Pfizer’s first quarter of top-line revenue growth on a year-over-year basis since the fourth quarter of 2022 when COVID-19-related revenues peaked.

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PFE Price Action: Pfizer shares were up 2.41% at $29.27 at the time of publication, according to Benzinga Pro.