It was fun while it lasted. Back in autumn 2007 PetroChina spent a glorious 31 days as the world's largest company by market capitalisation, toppling some sorely aggrieved Texans. Since then the Chinese company has fallen by two-thirds, while ExxonMobil has slipped by a quarter.

Taking a more dispassionate view of the China growth story, investors are now weighing a genuinely world-class operator against a fast-growing pretender, where the vast majority of production and sales are still domestic, and where capital discipline is often secondary to the ambitions of the government, holder of 87 per cent of the shares. PetroChina's price to book multiple of 1.4 is less than half that of Exxon's – a much bigger discount than the five year average. More simply, in market capitalisation terms, that's a big fat $46bn.

That is not to say that PetroChina has gained no traction over that period. Unlike more mature peers, which used much of the proceeds of the commodities bull market to buy back stock and spray off special dividends, PetroChina kept investing. Now, while other majors lop off a billion or two of capex here and there, PetroChina is still spending through the cycle. Full-year figures, released on Wednesday, showed that capex – two-thirds of it in the upstream – was up by 27 per cent last year to $34bn, and should stay flat in 2009. Of the international majors, only Shell ($31bn-$32bn) comes near it.