Troubled mining giant Anglo American announced its chief executive, Cynthia Carroll, is to step down from her role as chief executive.
Her resignation comes hot on the heels of the departure of educational publisher Pearson's female chief executive, Marjorie Scardino.
Just Burberry boss Angela Ahrendts, who took the reins at the fashion group in 2006 and Alison Cooper, chief executive of Imperial Tobacco since 2010, remain as female heads.
A recent report by Deloitte found that while more companies are appointing women to their boards - women claimed one-in-10 executive boardroom apointments over the past year - most join in non-executive positions rather than taking executive roles.
Before Carroll's departure was announced, the 30% Club , a group committed to bringing more women onto UK corporate boards, had said women accounted for 17.5% of FTSE 100 board positions, well below the 25% target set by Lord Davies, who led an inquiry into the male dominance of UK boardrooms.
Carroll is expected to remain in her role until a successor is found.
Despite being credited by her company in its market statement on 26 October with steering Anglo American through the economic crisis, and achieving record group profits in 2011, the last 12 months have been difficult for Carroll.
The chief executive came under pressure from shareholders in Anglo American who demanded an immediate change of management after losing confidence in her strategy and leadership.
In August, The Daily Telegraph reported several of the miner's biggest institutional investors have contacted Sir John Parker, the chairman of Anglo, to ask him to start the search for a new chief executive.
Anglo American had also been hit by a number of workers' strikes; Anglo American Platinum, the world’s biggest producer of the precious metal which counts Anglo as one of its major shareholders, dismissed about 12,000 illegally striking workers as industrial tensions have escalated in South Africa in recent weeks.
Despite this, the shareholders concerns were said to have been sidelined by Sir John, and the Financial Times reported on 26 October that Sir John has insisted Carroll's departure was solely "her decision".
Carroll said in a statement: "It is a very difficult decision to leave, but next year I will be entering my seventh year as Chief Executive and I feel that the time will be right to hand over to a successor who can build further on the strong foundations we have created."
And paying tribute to his colleague, Sir John said:"Cynthia's leadership has had a transformational impact on Anglo American... Her legacy will include, among many other things, a step change improvement in safety, sustainability and the quality of our dialogue with governments, communities and other stakeholders. Her values represent the very best of Anglo American."
Carroll will also relinquish her role as chairman of Anglo American Platinum and of De Beers when she departs.