He will be replaced by Liz Field, who takes over in September. Field was previously chief executive of the Financial and Legal Skills Partnership and has experience in wealth management and broader financial services.
She was previously CEO of the Financial Services National Training Organisation, the Banks and Building Societies National Training Organisation, and the Insurance Industry Training Council; and spent four years as head of organisational development at Gerrard.
Over the past four years, May has headed theWMA through the introduction of the retail distribution review and its renaming from the Association of Private Client Investment Managers and Stockbrokers.
WMA chair Tim Ingram said: 'Tim has done a fantastic job leading the WMA over the last four years, taking the organisation through a period of significant change, and we are sorry that he has decided to step down.
'The significant increase in recent times in the membership and profile of the WMA is a clear tribute to his achievement. We wish him the very best in his future endeavours.
'We are delighted to have secured someone of Liz Field’s calibre. Liz brings many years of experience in leading trade organisations, championing the work of sectors in the financial services area, together with a good knowledge of wealth management, having worked at Gerrard.'
May added: 'I’m proud of the WMA’s achievements on behalf of our community of firms and their four million clients. After four years of endeavour, backed by a great team of staff, I’m looking forward to assisting Liz up to our Annual Conference on six October 2014. I wish her and the community well for the future.'
Field said she was looking forward to taking over the WMA at an important time for the sector.
'Businesses operating in the wealth management sector are facing many challenges both in the UK and in the international market place. I am excited about helping the WMA membership to navigate through the many changes and challenges they are facing and to support in promoting the sector.'