Gay equality group Stonewall has published its annual Workplace Equality Index, showcasing the UK's top 100 employers for gay people.
Lloyds TSB was named the most improved employer in the index.
Larry Hirst, country general manager at IBM UK, said: "To be recognised by Stonewall as the leading UK employer for workplace equality is a source of tremendous pride. I'm convinced that the principles of diversity, inclusion and equality must sit at the heart of any truly modern, successful and confident organisation."
Employers were ranked according to criteria ranging from implementation of an effective equality policy to demonstrating how they engage with their lesbian and gay staff, customers and service users.
The index assesses actual practice, such as recruitment and mentoring activity, as well as just policy.
"Employers actively engaged in the talent market take workplace equality very seriously," said Stephen Frost, Stonewall's director of workplace programmes.
"They know Britain's 1.7 million gay staff and their colleagues now use this information in their career planning."