Thomas Cook (LON:TCG) shed a quarter of its market value following the shock resignation of chief executive Harriet Green.

Green, who departs immediately, told investors her work was complete - though this morning's share price reaction suggests the market may disagree.

She joined Thomas Cook two years ago - after the share price had slumped to just 14p, valuing the firm at £148mln - and she has since overseen a substantial turnaround in the group's fortunes.

"The transformation of Thomas Cook into a company with a market capitalisation of just under £2 billion and a share price of over 130 pence is one I have been proud to lead," Green said in a stock market statement.

"I always said that I would move on to another company with fresh challenges once my work was complete. 

"That time is now."

Green is being replaced by Thomas Cook's chief operating officer Peter Fankhauser.

Separately, Thomas Cook released audited results for the twelve months to September 30 which showed a 44% rise in underlying earnings (EBIT) to £323mln. Revenues were down at £8.5bn versus £9.3bn in the preceding year, however, the group's loss after tax narrowed to £115mln from £213mln in 2013.