The offer is split among its shareholders, broker firms and institutionals, who are expected to be allocated 50% of the deal.

Alinta boss Bob Browning's revamped growth strategy, which he roadshowed in recent weeks, has resulted in institutionals rising from 13% of the Alinta register to control almost 50% of the shares.

The current raising comes on top of the 42 million shares placed last month as part of US firm Aquila's exit from the WA based energy player.

Alinta will use the $125 million to fund the buyback and cancellation of its own shares from United Energy.