Instinet, the agency brokerage, warned that earnings and revenues for the current quarter will be lower than expected due to the destruction of the World Trade Center and worse-than-expected US equity share volumes.

The warning did little to deter investors on Monday, who returned forcefully to brokerage-related shares as well as other sectors sold off last week. At midday on Monday, Instinet shares were up 9 per cent to $11.20.

Instinet runs the largest alternative securities marketplaces that trades on a near-24-hour basis. But the company, like the rest of the trading sector, closed its fixed-income and equities trading operation in line with the broader markets. In the case of stock trading, the company lost four trading days.

Instinet is also dealing with other troubles as a result of the recent terrorist attack. Its backup trading floor and entire clearing operation occupied three floors of World Trade Center tower number one. In addition, two of the company's 214 staff from lower Manhattan remain missing.