Australia's sovereign wealth fund (SWF), the Future Fund has given its support to the $4.5 billion plan of buying Transurban.

In it the deal, Future fund is involved with and helping two Canadian pension funds to buy stake in the toll road operator.

After the news, the shares of Transurban went down by 6 per cent.

The talks between Transurban and Pension Plan Investment Board and Ontario Teachers' Pension Plan, have been going on for months. The two funds which already hold 28 per cent stake in the company, want to buy more stake by paying A$5.25 per share.

But Transurban rejected the bid saying that the Canadian funds wanted the existing shareholders to take 22 per cent stake in the company. This was unacceptable to it.

After the support of the Future fund, there is hope that something solid will develop out of the talk.

Future Fund at present has less than 1 per cent stake in the company.

People from the industry say that this announcement will surely push forward the talks. But ultimately it is the shareholders who will have to make some decisions.

Most important will be CP2's decision, which holds a significant stake in Transurban.