CVC Capital is thought to be plotting to buy ConvergEx, a US trading-software company, which is part-owned by Bank of New York Mellon.
A deal valued at $1.9bn (£1.2bn) may be announced as soon as this week, it emerged yesterday.
ConvergEx, formed through a merger in 2006, sells software products and technology-enabled services for asset managers and other financial firms. The firm had also been considering an initial public offering.
A spokesperson for ConvergEx declined to comment last night.