The Coca-Cola sign in Sydney's Kings Cross lights up in rainbow colours. Credit:Wolter Peeters "I think the job of business is firstly to create jobs and secondly to do good in society – this issue is part of that second category." Mr Pratt was joined by AGL chief executive Andy Vesey, who on Monday night addressed a function for LGBTI staff at Parliament House, twice declaring it the highlight of his high-profile day in Canberra. He said "inclusion for all" was central to the electricity provider's ethos. "We want to remind people of those values. We want all our people to feel welcome ... we want all our people to bring everything they have [to work] and not to have fear," Mr Vesey said. "But I will tell you something else – and I get into a lot of trouble for this – I am telling you that personally I am supportive, that personally I will stand up, personally I will put my name on this.

Cardboard billionaire Anthony Pratt says he will back same-sex marriage. Credit:Nic Walker "Because that's how the world changes – it changes by people willing to stand up and say what they believe. This is the right side of history, this is important to people." The expressions of support came as Qantas boss Alan Joyce, a vocal backer of same-sex marriage, donated $1 million to the "yes" campaign, the largest known financial contribution to either side so far. Meanwhile, as Coca-Cola lit up its famous Kings Cross sign in rainbow colours on Tuesday night, the company issued a statement in support of a "yes" vote. "Every person has the right to happiness, so we believe it's time for a change in Australia. No matter who you are or who you love, all couples should be treated equally," it said.

Its Sydney-based regional president Roberto Mercade said it was "the right time" for his firm to stand up for same-sex marriage. "We've always stood for diversity, inclusion and quality," he told Fairfax Media. "It's part of the DNA of people having the right to happiness and respect for each other's points of view. "We want to make sure that we represent our consumer base, and our consumer base throughout the world is extremely diverse." And the US-based tech giant Apple weighed into the Australian debate on Tuesday, backing a "yes" vote in line with its longstanding support for same-sex marriage. "We support marriage equality and believe all Australians deserve the freedom to marry the person they love, and to have their relationships recognised with the same dignity and legal protections as their neighbours, friends, and family," the company said.

The Coalition for Marriage has argued corporate support for same-sex marriage shows the "no" side is in a David versus Goliath battle against the establishment. Despite business leaders' best wishes, Equality Campaign director Tiernan Brady said corporate Australia was making a "minuscule" contribution to the "yes" campaign. "We haven't received any significant corporate donations," he said. "We'd be surprised if we get $100,000." Behemoth search engine Google placed a link on its Australian home page – the country's most visited website – directing readers to the Australian Bureau of Statistics' survey webpage and urging them to "make your voice count". But the company declined to publicly comment on the issue, despite a long track record of supporting gay rights. It is listed as a corporate supporter of Australian Marriage Equality and was a financial backer of this year's Sydney Gay and Lesbian Mardi Gras.