Walgreens Boots Alliance said Friday CEO Rosalind Brewer has stepped down less than three years since she took the top job at the pharmacy chain operator.

The company's board and Brewer had mutually agreed that she would step down, Walgreens said, without providing further details.

Brewer, a former Starbucks executive, joined Walgreens in 2021. She oversaw the rollout of COVID-19 vaccines and also struck a series of deals to push further into healthcare and operate doctors' offices.

But the benefit from COVID testing and vaccine sales has tapered off and Walgreens' stock has fallen in recent months.

The company in June warned that lower spending by inflation-weary consumers and a hit from a larger-than-expected drop in COVID-19 product sales would likely persist into next year.

Walgreens' shares have lost about 47% of their value since March 2021, when Brewer became CEO.

The company named Lead Independent Director Ginger Graham as interim chief executive and said it had launched the search for a permanent CEO.

Brewer will continue to serve the company as a special adviser through February 2024, pursuant to which she will receive a monthly consulting fee of $375,000, Walgreens said.

The pharmacy chain operator added that it expects full-year 2023 adjusted earnings per share to be at or near the low end of its previously stated range. The company's shares were marginally higher in volatile premarket trading.