British publisher Pearson, which recently struck deals to sell the Financial Times newspaper and The Economist magazine, cut its annual earnings forecast on Wednesday, causing its share price to slump.

Pearson was down a hefty 16.25 percent at 995 pence, making it by far the biggest loser on London's benchmark FTSE 100 index, which was down by only 0.27 percent at 6,329.79 points in morning deals.

Pearson said it expected full-year adjusted earnings of 70-75 pence a share, down from an earlier forecast of 75-80 pence.

"The disposal of (online education tool) PowerSchool, FT Group and The Economist Group, as well as movements in exchange rates, reduces this range by approximately five pence" for 2015, Pearson said in an earnings statement.

"Given a strong competitive performance but continued challenging market conditions, we expect our adjusted earnings per share to be around the bottom end of this range," it added.

Pearson earlier this year agreed to sell its 50 percent stake in The Economist Group, owner of prestigious magazine The Economist, mainly to Italian investment firm Exor.

It agreed also to sell the Financial Times newspaper to Japanese digital media group Nikkei.

The twin sales form part of major restructuring at Pearson, which wants to focus solely on its education publishing business.