The former Kidman Resources chief executive Martin Donohue “is the most likely source” of inside information relied on by his brother-in-law Duncan Stewart to buy shares in the lithium miner, the corporate regulator has claimed in court.

The Australian Securities and Investments Commission alleges Mr Donohue told Mr Stewart of Wesfarmers’ $776 million plan to take over Kidman Resources before the information was made public, and that Mr Stewart used this knowledge to buy Kidman Resources shares twice in April 2019.