Mark initially trained and qualified as a real estate valuer at Auckland University while working with a commercial real estate agency from 1967 to 1981. From 1981 until 1984 he worked for the Hong Kong Government as an Estate Surveyor in the New Territories and returned to New Zealand to work with a Hamilton real estate agency for the next seven years until 1992.
Mark established the first Bayleys Real Estate franchise in New Zealand and ran this agency for 13 years. He then sold the business to establish Oyster Property Group in order to specialise in the syndication of commercial property which he had been increasingly moving towards during the previous 20 years.