Oprah exiting WeightWatchers

Oprah Winfrey is leaving WeightWatchers board of directors and donating all of her interest in the company to a museum.

Shares of WW International Inc. tumbled more than 23% in Thursday morning trading.

Winfrey, who told People magazine in December that she was using a weight-loss medication, has served on the company's board since 2015. She will not stand for reelection at WeightWatchers annual meeting in May.

WW International said in a regulatory filing that Winfrey's decision “was not the result of any disagreement with the company on any matter relating to the company's operations, policies or practices.”

The size of its board will go from 10 to nine members following its annual meeting, the New York company said.

According to FactSet, Winfrey's stake of about 1.1 million shares made her the company's largest individual shareholder, with a stake of 1.43%.

Winfrey said that she will donate her interest in WeightWatchers to the National Museum of African American History and Culture, part of the Smithsonian Institution in Washington.

The company said that it supports Winfrey's decision to donate all of her stake to the museum during WeightWatchers upcoming trading window this month.