(Reuters) - CVS Health ( CVS ) CEO Karen Lynch is stepping down after nearly four years at the helm, as the healthcare conglomerate faces shareholder pressure to improve its business performance.

Lynch, who was the head of its Aetna insurance unit before taking over as CEO, will be replaced by company veteran David Joyner.

CVS stock has lost nearly 26% of its value this year due to multiple cuts to the firm's annual profit forecast.

Here is a timeline of key events for CVS during Lynch's tenure:

Feb. 1, 2021

Karen Lynch begins her role as CEO in the midst of the COVID-19 pandemic.

Feb. 9, 2022

The company's shares trade near 7-year highs as its drugstores benefit from high demand for COVID-19 vaccines.

Aug. 3, 2022

CVS Health ( CVS ) lifts its annual outlook for COVID-related revenue as it expects sales of over-the-counter tests to more than double through the year.

Sept. 5, 2022

CVS agrees to buy home healthcare services company Signify Health for about $8 billion in cash.

Feb. 8, 2023

CVS says it will buy primary care provider Oak Street Health for about $9.5 billion in cash as the pharmacy giant looks to foray into the urgent care business.

May 3, 2023

CVS says it will pause acquisitions to focus on integrating purchases of healthcare service provider Signify Health and primary care provider Oak Street Health.

Aug. 2, 2023

CVS cuts 5,000 non customer-facing roles and shuts its clinical trials services as part of a plan to cut costs.

Nov. 1, 2023

CVS cuts the profit forecast it gave in August to account for potentially higher medical costs at its insurance unit.

Dec. 5, 2023:

CVS forecasts 2024 revenue above market estimates and says it will simplify the structure through which its pharmacies get reimbursed for drugs, in a push for transparency amid scrutiny on surging healthcare costs.

Feb. 27, 2024:

CVS cuts its 2024 profit forecast due to an increase in Medicare-related costs.

April 2, 2024:

Final 2025 rates for Medicare Advantage payments by the U.S. government imply a cut, triggering worries among investors in the sector about a margin squeeze.

May 1, 2024:

CVS cuts its profit forecast again.

Aug. 7, 2024:

Shares tank after yet another cut to its profit forecast. CVS says it expects medical costs to stay high through the year.

Aug. 14, 2024:

A regulatory filing shows that investment firm Sachem Head Capital Management built a new stake in CVS in the second quarter.

Sept. 29, 2024:

The Wall Street Journal reports that hedge fund Glenview will meet top executives at CVS Health ( CVS ) to propose ways it can improve operations. Reuters later reports the company is exploring options to improve performance.

(Reporting by Christy Santhosh in Bengaluru; Editing by Devika Syamnath)