Network management start-up RiverSoft is aiming for an IPO in London before Christmas.The three-year-old company is understood to be trying to raise $100m to develop its software, invest in marketing and to use as working capital. However, the company is refusing to comment on a possible valuation of £400m, quoting US regulator SEC's rules which limit disclosure of such information before a prospectus has been issued. A spokesman explained that although the company is listing in London, it will be raising some of the cash in the US. RiverSoft is backed by heavyweight US IT companies HP, Cisco and Intel. Its software promises an interventionless management of complex IP networks. Revenue this year was near £1m and showed a steeply rising trend. None of its backers intend to sell any shares. RiverSoft's customer list includes Barclays Global Investments, British Airways, Colt and Deutsche Bank. The company has already raised $50m from venture capitalists Apax Partners, Morgan Stanley and others and has 200 staff in New York, London and San Francisco.