Lucy Turnbull has increased her stake in Prima BioMed shortly after talking of "difficult times" as far as the share price was concerned.
"We appreciate our investors' support of the very important work we do here at Prima, trying to harness the immune system to fight and control cancer," the chairman told shareholders at the company's annual meeting.
"We know it has been a trying year for shareholder value."
The next business day she put $95,000 into the stock, paying 4.1¢ - a 63 per cent discount on the stock's 52-week high of 11¢.
The group's chief executive officer has also been a buyer.
Prima has more than 1.2 billion pieces of paper floating around; the group is valued at about $50 million.
Overall directors' trading registered $3.3 million to $28.7 million in favour of sellers.
Helping the sellers' tally along was James Murdoch who sold about $16 million of 21st Century Fox shares.
Nick Scali, who more than five decades ago founded the business bearing his name and who is now a non-executive director and consultant, collected $3 million and now has zero shares.
The family still has a decent slice of stock: managing director Anthony Scali holds 40.5 million shares.
Moko Social Media scrip has been on fire recently and there was more activity in the stock this week.
Managing director Ian Rodwell did a mighty profitable options trade, exercising them at 4.2¢ and selling at 21.5¢.
He said he had sold to pay costs on his proposed relocation to America and any tax obligations arising from the sale.
Fellow director Peter Yates appears to have bought options from Mr Rodwell.
Scrip in the developer of customised mobile community applications hit a 33¢ high on Thursday.