Corporate Singapore was rocked back on its heels last night with the news that Singapore Post group chief executive Wolfgang Baier had quit.

Dr Baier, who was in the post for just four years, has "left to pursue new endeavours", according to the firm in a statement to the Singapore Exchange. The abrupt departure, which apparently came with no notice, has surprised markets, given the successful turnaround he has delivered at SingPost.

Dr Baier, 41, an Austrian who moved to Singapore in 2004, said in a statement last night: "I am moving to new endeavours and will ensure a smooth handover before I leave."

He joined as chief executive of international operations in February 2011 and was appointed group chief executive in October that year.

With Dr Baier leading what he called a "transformation for survival" as the firm sat on a "burning platform" of falling mail volumes, SingPost snared Alibaba as a shareholder and made key acquisitions, including American e-commerce service TradeGlobal last month.

Alibaba even agreed to raise its stake in the group.

SingPost, which has been held up by many as the poster child for old industries that are reinventing themselves for the digital age, vindicated the faith placed in it by analysts when it unveiled bumper results last month.

The firm reported a 27 per cent jump in half-year net profits from a year ago, boosted by one-off gains from divesting of subsidiaries, and its growing e-commerce business.

While SingPost searches for a new group CEO, deputy group CEO for corporate services Mervyn Lim will take over Dr Baier's duties.

Deputy chairman Goh Yeow Tin will be roped in as an executive director from Jan 1 for 12 months to oversee SingPost's post-merger integration activities and operations in Singapore.

SingPost chairman Lim Ho Kee will also give the management team "more time and guidance" as SingPost continues its transformation from a local postal service to a regional e-commerce and logistics group.

Dr Baier joined SingPost with 10 years of experience at consulting firm McKinsey's postal and logistics divisions in Europe and Asia.

He is seen by many as the face of change at SingPost but has always resisted the attention.

Dr Baier told The Straits Times last year: "It's less about myself. In the first year of transformation, one needs to lead. But then you need to empower a team... A single person cannot sustain the change." He even asked that the interview be run without his photo but alongside pictures of SingPost's innovations instead.

Mr Lim said: "Under Wolfgang's leadership and great team effort, SingPost has been established as a regional leader in e-commerce logistics business, with a strong focus on digitising our business."

The resignation was announced after market close. The counter closed down 0.02 cent or 1.13 per cent at $1.755.