Danish pension fund AkademikerPension said on Monday it was selling its stake in budget airline Wizz Air (WIZZ.L) over alleged “human and labour rights abuses” towards its workers.

The $23 billion fund was one of 14 investors that called on Wizz in December to allow employees to form and join trade unions, saying their research suggested it was discouraging the practice in breach of staff rights.

AkademikerPension said on Monday that, after meeting management, it saw no sign the airline’s practices would change, and so it had begun to divest its holding, worth more than $3 million. The market value of London-listed Wizz Air is around $5.8 billion.

The fund said it had sold the shares it directly held in Wizz Air on Feb. 1, and had given its external fund managers until Feb. 8 to do the same.