Southwold brewer Adnams has cut its ties with the CBI after the organisation became engulfed in scandal.
The brewing and pubs group - which prides itself on its social responsibility - said it was "unsustainable" to remain as a member.
It is one of a series of top names to cut ties with the organisation, including Asda, Shell and Aviva.
The CBI has been rocked by a series of scandals in recent weeks with allegations of sexual harassment, bullying, drug-taking - and even rape.
It has admitted a "toxic" culture and its director-general Tony Danker has been sacked and replaced by Rain Newton-Smith. She said she is "profoundly sorry" for what has happened and promised reform.
Adnams chief executive Andy Wood said: "Adnams is a business that sets high standards for itself and its business partners.
"As an organisation that is vocal about responsible business behaviour and that expects adherence to a set of core values from its team, it has become unsustainable for us to remain members of the CBI.
"It is crystal clear the CBI has some engrained cultural and behavioural issues to deal with and this further series of allegations has led us to the decision to withdraw our support."
The CBI said it shared "the shock and revulsion at the events that have taken place in our organisation, and at past failures that allowed these events to happen".
It has suspended all policy and membership activity until an Extraordinary General Meeting (EGM) in June and said it would take time to rebuild trust.
A CBI spokeswoman said: "We recognise that we need to be better and do better for our members and we will now work tirelessly to ensure that under new leadership and with a commitment to build a modern, inclusive culture, the CBI can and will resume its vital work of supporting British business.
"We hope that our members will be part of that journey with us."
Adnams is continuing to promote its social responsibility agenda.
Adnams Community Trust has just announced its latest grants round is open for applications.
The trust - which has been in operation for 32 years- supports worthy causes across a wide range of community activities from environment to health and social welfare within a 25-mile radius of the Adnams HQ.
Its income comes from a percentage of profits from Adnams, donations, legacies and the from Adnams customers who donate through Pennies in Adnams shops.
Trust chairman Jonathan Adnams said: "These are economically challenging times for everyone and, modest through they are, our grants make a real difference to the lives of people in our community.
"That the Adnams Community Trust has been able to continue its work is thanks in no small part to a very generous legacy left to the trust by a former shareholder, Leona Levine, and the generosity of Adnams customers when they donate through Pennies in Adnams shops and online.”
Grants range from £100 to £2,500 and must be for specific items. They are awarded four times a year, in January, April, July and October. Information on how and when to apply can be found at adnams.co.uk/pages/act-grants
The deadline for the next round of awards is May 10, 2023, and will be decided in July 2023.
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