From the article:

> A profitable IPO is meant to anchor a sovereign wealth fund that will, if things unfold as envisioned, generate enough investment income at home and abroad to dominate state revenue by 2030. Demand for oil will peak just before then, according to Royal Dutch Shell Plc projections, as alternative fuels and electric cars gain popularity, putting Middle East energy producers on shakier footing.

So, it sounds like they want to turn their oil reserves into cash before the price of oil begins to fall.

My assumption is to prevent any future sanctions against the Saudi regime. Once the markets and 401Ks are invested in the Saudi oil, the US government will have a lot less options to put sanctions on them as the Wall Street powerful lobby system will block it.

They need cash now. Think of it as preselling oil.

They need money.