(Reuters) -WiseTech Global ( WTCHF ) said on Monday it was reviewing a "full range of matters" concerning its CEO after media reports made allegations about his personal life including payments to a past sexual partner, sending its shares slumping 18%.

The Australian Financial Review and other media outlets reported that a woman who had a sexual relationship with the billionaire chief made a raft of claims against Richard White in late 2020, including allegations that he had engaged in inappropriate behaviour.

Shares of the Australian technology firm dived as much as 18.3% to A$100 and were on track for their worst trading session since late August, 2023.

White, WiseTech's billionaire founder and major shareholder, could not immediately be reached for a comment while WiseTech did not immediately respond.

The reports said White, 69, had approached numerous female entrepreneurs through text messages and social media with offers of professional support that could shift into crude or suggestive language.

The growing media attention on White's private life, with media reports continuing to emerge, has now begun to impact the firm's reputation with its shares falling over 11% since the beginning of the month.

WiseTech said it was seeking further information and taking external advice.

"It is conscious of the potential impacts on the company and will carefully evaluate all relevant factors in its assessment," the tech major said.

White has also continued to sell down his stake in the tech company. In the latest sell-off, White sold 351,038 shares at an average price of A$131.22 apiece between Oct. 11 and Oct. 17, according to a notice filed on Friday.