Siang joined DAS on 15 December 2001 and assumed the post of CEO on 1 September 2014. He also sits on the Board of DAS subsidiaries, DAS Academy and DAS International.  Siang was a member of the US-based International Dyslexia Association from 2016 to 2018 and Chair of their Global Partners Committee from 2016 to 2018, he still remains a member of the Global Partners Committee representing Singapore.  He has played a key role in the rapid growth of DAS into a thriving social enterprise with a multi-disciplinary professional workforce that provides a continuum of services.  He emphasizes that DAS "must strive to fulfil our social mission by combining entrepreneurial and business skills with the philanthropic characteristics of non-profits".
 
Siang obtained his BA from the National University of Singapore via the sponsorship of the Singapore Armed Forces. He also has a Certificate in Dyslexia Studies, a PGC in Teaching and Learning in Higher Education and a PGC in Specific Learning Differences from London Metropolitan University, a PGDip in Financial Management from the Singapore Institute of Management and an MBA from the University of Western Australia. It is this unique balance of experiences and qualifications that have allowed Siang to oversee the diverse services and functions of the DAS family.