ABP's South Wales Ports director Budha Majumder has left his job with immediate effect citing "personal reasons".
The popular businessman was in charge of ABP's port facilities from Newport to Swansea for the last two-and-a-half years.
Most commentators regard his work for the national operator as a great success during a period of significant change.
He was an excellent ambassador for ABP and engaged the business community in a number of ways. He was, for example, an active member of the Cardiff Business Club.
Mr Majumder has returned to his Wirral home and is reluctant to elaborate on the reasons for his departure.
ABP is normally a very communicative company but in this instance it had nothing to say, apart from naming Mr Majumder's successor.
He is John Copping, 56, a former ABP South Wales director who has recently been working for the company in Grimsby.
He will take up his new post on September 1.
ABP is currently facing the prospect of a national dockworkers strike as its latest pay offer has been rejected by a union ballot.
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