Reading the various interpretations of Chinalco’s extraordinary dawn raid on Rio Tinto, and seeing the Chinese corporation’s explanation in Sydney yesterday, one is left open-mouthed by the audacity of China’s move, but rather hazy on what exactly it wants to achieve.

It’s hard to imagine a more seismic business coup. Entering the world's biggest bid battle just days before a “"put up or shut up” deadline is about as dramatic as it comes. The £7 billion in cash paid for the Rio stake spells out how seriously the Chinese regard this foray. But Chinalco’s boss, Xiao Yaqing, has given so many reasons for the move that Rio shareholders are not quite sure what his motivation is. His claim that the timing was just “coincidence” has also raised eyebrows, though perhaps one can blame the interpreters for that one.

Theory one is that the Chinese want to keep supplies of iron ore plentiful and its future price cheap. They are terrified that a merger of Rio and BHP Billiton could create a stranglehold. The 12 per cent Rio stake, plus the firepower to buy much more, gives them the ability to block a Rio-BHP tie-up even if one can be agreed. China is separately investigating how the merger could be blocked on competition grounds. But while Washington and Brussels could make a deal difficult, there is no global anti-trust regulator to veto the deal.

Theory two is that the Chinese want to secure supplies of bauxite, alumina and aluminium, the main products of Chinalco, and are prepared to pay any price to get them. They see Rio, which bought Alcan of Canada last year, as a perfectly digestible acquisition, maybe not this year, but one day. The raid gives them a solid foothold.

Theory three is that while Rio is too difficult a prize — the Australian Foreign Investment Review Board is unlikely to favour a foreign acquisition of such a jewel in the country’s corporate crown — Chinalco now has a seat at the table. It should be able to parlay its stake into significant Rio assets in the event of anyone else buying the company. Chinalco’s overture to BHP on Saturday supports this theory.

According to the Chinalco camp, all these are options and more besides, including the need to diversify or simply to make a nice financial turn: Beijing believes in the commodities super-cycle, as well it might, since its own factories are the engine that will keep the momentum going. The flurry of resources deals in recent weeks certainly suggests that the Party is looking kindly on resources investment.

But to assume Chinalco will act like a conventional Western corporation would be a mistake. We know virtually nothing about its governance or goals, let alone those of the politicians who ultimately control it.

Is it looking to maximise profits? To maximise production? To maximise dividend payments to its sole shareholder, the Chinese state? To what extent is Mr Xiao, a senior party official as well as an engineer and businessman, motivated by profits or more of a cypher through whom Beijing policy is conducted?

As Chinese corporations continue to purchase their way on to the shareholder registers of Western companies, questions like these are going to multiply.

In one sense it is encouraging that Beijing is buying — literally — into joint-stock capitalism. But it would be naive to assume its business leaders are motivated by the same forces as their Western counterparts.

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