Shares in publisher Pearson fell almost 10 per cent in early trading, after a broker downgraded it to "underperform".
Exane, which has historically been a supporter of Pearson, downgraded the company as its shares went ex-dividend, meaning stock bought from today no longer has the right to the latest dividend.
Shares in the publisher were down 9.3 per cent in mid-morning trading, at 618.8p. That means shares in the company have fallen almost 36 per cent since they peaked in July last year.
The downgrade came just over a month after Pearson posted figures showing sales had fallen eight per cent during a "challenging year", with profits falling 21 per cent to £635m. That followed a trading update in January, when shares tumbled 30 per cent after it withdrew its profit goal for 2018, citing "portfolio changes and challenging and uncertain markets".
This morning Ian Whittaker, media analyst at Liberum, warned there were more woes to come.
"Our view is that Pearson is likely to have a profit warning in 2017 and that aggressive cost cutting runs the risk of damaging the business further, after severe cost cutting in 2016," he said.
"At circa 15 times full-year 2017 adjusted [price to earnings ratio], the shares are very expensive given the structural pressures and definitely at too high a multiple for the pressures it faces."