CMC Markets Plc shares slumped as much as 20% after the financial derivatives dealer’s full-year guidance fell short of estimates.

The London-based firm said subdued trading conditions continued through August, with trading and investing net revenues trending 20% lower year-on-year. It now sees net operating income between £250 million and £280 million, according to a statement. Consensus was for £334.8 million.

“August in particular has seen a more challenging environment with markedly lower monetization of client trading activity due to a higher proportion of lower margin institutional volume,” the company said.

Before today, the stock had lost 46% so far this year.