This seems like a particularly bad article, especially considering that it's published in a business publication. While the article does say:

Norway derives about 20 percent of its economic output from oil and gas. Finance officials have long debated whether reinvesting those profits back into petroleum producers leaves Norwegians overly exposed to the volatility of oil prices.

It fails to state clearly that the only reason that Norway has a $1 trillion dollar surplus of funds is because of their oil wealth. They are divesting from oil stocks due to simple goal of diversification, to prevent the Norwegian economy and the fund from being too closely coupled. While it's gauche to quote Wikipedia as the arbiter of truth:

The Government Pension Fund Global, also known as the Oil Fund, was established in 1990 to invest the surplus revenues of the Norwegian petroleum sector.

The Government Pension Fund Global (Norwegian: Statens pensjonsfond Utland, SPU) is a fund into which the surplus wealth produced by Norwegian petroleum income is deposited. Its name changed in January 2006 from the Petroleum Fund of Norway. The fund is commonly referred to as the Oil Fund (Norwegian: Oljefondet).

The purpose of the fund is to invest parts of the large surplus generated by the Norwegian petroleum sector, mainly from taxes of companies but also payment for licenses to explore for oil as well as the State's Direct Financial Interest and dividends from the partly state-owned Statoil. Current revenue from the petroleum sector is estimated to be at its peak period and to decline in the future decades. The Petroleum Fund was established in 1990 after a decision by the country's legislature to counter the effects of the forthcoming decline in income and to smooth out the disruptive effects of highly fluctuating oil prices.

https://en.wikipedia.org/wiki/Government_Pension_Fund_of_Nor...

The most charitable interpretation I can come up with is that BloombergMarkets assumes that everyone bothering to read the article already knows this. But somehow I doubt this is true, and that the authors were actually making this assumption. So why is it written this way? Spin, ignorance, or just bad editing?