A banker is suing HSBC for £5m, claiming the bank fired him for being gay.
Peter Lewis was global head of equity trading at the investment bank until he was fired for gross misconduct in February.
It is the largest claim yet to be made under the sexual orientation legislation that came into force last December.
Lewis’ lawyer, Alison Downie of solicitors Bindman and Partners, said her client "was dismissed when HSBC discriminated against him because of his sexual orientation as a gay man".
HSBC has said that it will "defend the claim vigorously".