Macquarie, a global investment banking and diversified financial services group, has hired investment bank Nomura for the sale of its 26% stake in UK Thames Water.

According to sources, the deal could be closed for a total amount of approximately £3 billion (US$4.25 billion).

Thames Water's shareholders, including BT pension fund, Abu Dhabi Investment Authority and the China Investment Corporation, have the option of first refusal before external buyers could bid for Macquarie's 26% stake.

Thames Water is the private utility company responsible for the public water supply and waste water treatment in large parts of Greater London, the Thames Valley, Surrey, Gloucestershire, Wiltshire, Kent, and some other areas of the United Kingdom. The company is the UK's largest water and wastewater services company, which supplies 2.6 gigalitres of drinking water per day and treats 4.4 gigalitres of wastewater per day. Thames Water's 15 million customers comprise 27% of the UK population.

In 2006, RWE, a German electric utilities company based in Essen, sold Thames Water for £8 billion in 2006 to Kemble Water Holdings, a consortium established by one of Macquarie’s infrastructure investment funds. Since 2006, Macquarie has reduced its stake in Thames Water gradually.