SoftBank Group Corp shares tumbled 5.5 percent on Monday, hurt by worries over its ties to Saudi Arabia as well as a broader market sell-off.
Saudi Arabia, which provided much of the funding for the SoftBank Vision Fund, is seeing a growing number of attendees pull out of the "Davos in the Desert" investment conference after the disappearance of a prominent Saudi journalist.
"With misgivings emerging about Saudi involvement in the journalist's disappearance, SoftBank's stock price is responding negatively," said Takashi Oikawa, an analyst at Ichiyoshi Securities.
The benchmark Nikkei index was down 1.4 percent in morning Tokyo trade as investors fretted over Sino-U.S. trade disputes and a possible slowdown in the Chinese economy.
With its Saudi ties causing jitters, SoftBank selling is "more psychological than anything related to worries on its fundamentals," said Makoto Kikuchi, chief executive of Myojo Asset Management.
SoftBank's influence under Chief Executive Masayoshi Son was built through its tech investments around the world, with the company last year raising more than $93 billion to create its Vision Fund - with $45 billion coming from Saudi Arabia.
That tech exposure has contributed to volatility in SoftBank shares over the last week as tech shares came under selling pressure.
A SoftBank spokesman declined to confirm if SoftBank executives are still planning to attend next week's conference, which has become the biggest show for investors to promote Saudi Crown Prince Mohammed bin Salman's reform vision.
Key SoftBank executives listed as attendees include Son, the head of the Vision Fund Rajeev Misra and ARM Holdings CEO Simon Segars.
Dara Khosrowshahi, CEO at Uber Technologies Inc - which is currently SoftBank's biggest bet, said last week he is no longer attending.
