(Reuters) -Activist investor Starboard Value has taken a stake of about $1 billion in Pfizer and wants the U.S. drug giant to make changes to turn its performance around, sources familiar with the matter said on Sunday.

Starboard has also approached Ian Read, a former Pfizer CEO, and Frank D'Amelio, who served as CFO until 2021, and both have expressed interest in helping the activist investor, the sources said.

Read served as CEO until Albert Bourla took the position in 2019. Bourla was instrumental in working with BioNTech to develop a COVID-19 vaccine.

Pfizer declined to comment and Starboard did not immediately respond to a Reuters request for comment.

Shares of the drugmaker rose 2.2% to $29.20 in premarket trading on Monday. They have fallen over 13% in the past year and trade at around half their pandemic-era highs as sales of its COVID products shrink.

Wall Street analysts said there was no quick fix by an activist investor to solve Pfizer's many problems.

"We await future developments, but we do not see low-hanging fruit to boost shareholder value," Leerink Partners analyst David Risinger wrote in a research note.

Pfizer has struggled to find a product that would make up for the lost revenue from its COVID vaccine and pill.

It had a weaker-than-hoped launch of its respiratory syncytial virus (RSV) vaccine and clinical data from an obesity pill it was developing has been disappointing.

CEO Bourla has also spent some $70 billion since 2020 on acquisitions, while launching cost-saving initiatives.

Pfizer bought Seagen for $43 billion, Biohaven for $13 billion, Arena for $6 billion, Global Blood Therapeutics (GBT) for $5 billion and Trillium for $2 billion.

The Wall Street Journal first reported the news of Starboard's stake.

The investment firm has previously pushed for changes at News Corp, Salesforce and Tinder-owner Match Group.

(Reporting by Svea Herbst-Bayliss in New York, Surbhi Misra and Kashish Tandon in Bengaluru; Editing by Tom Hogue, Jacqueline Wong and Anil D'Silva)