Healius chief executive Maxine Jaquet says higher rents and wages have upended the pathology testing group’s economics while revenue growth is becoming harder to generate, as she defended the company’s performance against criticism from Tanarra Capital.

The investment fund, founded by former Lazard managing director John Wylie, is Healius’ second-largest investor and has an 8.5 per cent stake in the company. It is demanding a major overhaul and is angry at the collapse in the group’s profit margins and share price.