Overseas investors have faced a setback in their proposed takeover of Origin Energy. 

AusSuper has rejected foreign firms Brookfield and EIG’s sweetened $20 billion bid for the company.

AusSuper, Origin's largest shareholder, was not convinced by the increased offer of $9.53 per share, making it challenging to achieve the required 75 per cent acceptance at the upcoming shareholder vote on November 23.

Brookfield and EIG had intended to split Origin's assets and invest between $20 billion and $30 billion in clean energy and storage. 

Luke Edwards, head of Brookfield's renewable power and transition group in Australia, has warned that shareholders voting against the deal were hindering Australia's energy transition.

Other institutional shareholders have reportedly indicated their support for the revised offer, while some remain undecided. 

A new option negotiated by Brookfield and EIG allows for a lower off-market takeover offer within six months if their agreed deal is rejected, potentially influencing Origin's share price.

The improved offer, declared “best and final”, is just above the upper end of independent expert Grant Samuel's valuation of Origin. 

Despite the rejection by AusSuper, the deal will be put to a shareholder vote on November 23.

The acquisition still requires clearance from the Foreign Investment Review Board, and the implementation date has been delayed to January 31, 2024.