Norges Bank which manages Norway's $1 trillion rainy day fund known as the Government Pension Fund Global has lifted restriction on several stocks it had previously banned on ethical grounds.
Following the news, pre-market and European trade showed a rise in all of the stocks except Mexican conglomerate Grupo Carso.
Norway's oil fund claims to hold an average of 1.4% of all the world's listed companies. It reached a $1 trillion value in 2017 and is in place to safeguard Norway's oil wealth, long after the hydrocarbons run dry.
Walmart shares had been excluded in 2006 after the fund's ethical advisers had then assessed the firm was guilty of a series of human rights. The press release, issued Tuesday, said "grounds for exclusion are no longer present."
The ban on Rio Tinto related to environmental damage at a mine in Indonesia. Norges Bank said the mining firm had now made it clear it planned to sell the mine.
"Re-introduction into the benchmark index will take place within an appropriately long timeframe. If and when share purchases will take place is left to Norges Bank to decide," the statement added.
Norway's oil fund has refused to buy shares of U.S. defense contractor General Dynamics since 2005 because the firm produced cluster munitions — bombs that release hundreds of smaller bombs. The firm has said it no longer makes that type of explosive.
Grupo Carso, which is owned by Mexican billionaire Carlos Slim, is also off the exclusion list after it said it was no longer involved in tobacco production.
Nutrien, a potash company, was previously banned after the fund expressed concerns over its purchases in Western Sahara.