Macquarie says new investor brings £300 million to Southern Water
Macquarie Group Ltd on Monday reported that a new shareholder will provide further funding to UK utility Southern Water.
The Sydney-based banking and financial services company agreed to buy a majority stake in the utility company back in August 2021.
Led by Macquarie Asset Management, a consortium is providing an additional £300 million in equity to Southern Water, which supplies customers in the south and south-east of England.
The latest equity injection is from funds managed by Asterion Industrial Partners, a Madrid-headquartered infrastructure investment firm, which Macquarie said has around $10 billion in assets under management. As part of the funding agreement, AIP will acquire a 20% stake in Southern Water, subject to regulatory approval.
This follows £900 million Macquarie committed in 2025, as part of a £1.2 billion support packaged disclosed last July. It will bring the total equity investment into Southern Water by Macquarie Asset Management-managed funds and co-investors to more than £2.8 billion, since MAM acquired Southern Water.
Macquarie stressed that Southern Water has continued to make progress with its turnaround strategy, which it says has picked up in 2026, the first year of the 5-year cycle under which UK water companies operate.
Like its peer Thames Water, from which Macquarie divested in 2017, Southern Water has grappled with debt, which PA reported in the region of £9 billion, as of July 2025.
In March, Southern Water was among five firms in the UK which were not allowed to hike bills by as much as they had requested, following a decision by the UK Competition & Markets Authority.
That decision came after the UK water regulator Ofwat in November blocked bonus payments to the bosses of several firms, including both Soutern Water and Thames Water, based on performance and pollution issues.
Martin Bradley, senior managing director at Macquarie Asset Management commented on Monday: ‘A year ago we set out a clear commitment to Southern Water and today‘s announcement of an additional £300 million of equity support delivers the full £1.2 billion investment package announced in 2025. We are pleased to welcome Asterion Industrial Partners as a new minority shareholder, reflecting growing confidence in Southern Water’s management team, its progress and its future plans.
‘While there is more to do, the focus remains on continued delivery. This capital supports the sector‘s largest growth programme relative to its size, with the company doubling the investment per household in the region for the benefit of its customers and the environment.’
AIP Chief Executive Jesus Olmos added: ‘This transaction marks Asterion’s entry into a new sector in one of our core geographies, and is fully aligned with our strategy of backing essential infrastructure with long-term capital and industrial expertise. We see a strong opportunity to support Southern Water‘s operational improvement, while contributing to the long-term resilience of critical infrastructure in the UK.’
Macquarie shares closed 0.8% lower at A$247.92 on Monday in Sydney.
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