Broker Tullett Prebon said trading activity has slowed in recent weeks, leaving its revenue for the year flat on last year, after a stronger trading period to the end of last month.
Tullett said in an emailed statement that revenue for the four months to the end of October was 8 percent higher than last year at £315m.
But the broker added: "Market activity slowed towards the end of the period, and revenue in the month of October was 3 percent lower than in October 2010. The trend seen in October has continued into November."
Tullett said its year-to-date revenue to the end of last month was £769m, flat on the same time last year.
The statement came two days after Tullett's main British rival ICAP said its revenue for the six months to the end of September was also flat on last year at £867m, while profit inched up two per cent to £186m.
"We are living through extraordinary times in financial markets. Global imbalances and slowing economic activity are being played out together with the Euro zone crisis," ICAP chief executive Michael Spencer said on Wednesday.
"The climate of uncertainty is inevitably creating risk aversion in volatile markets around the world," he added.