International investors were the biggest purchasers of shares in Saudi Arabia last week, when oil giant Saudi Aramco started to be added to main gauges tracking emerging-market equities.

Investors from outside of the Gulf were net buyers of about 3.56 billion Saudi riyals ($950 million) for the week ended Dec. 19, according to data provided by the stock exchange. Qualified foreign institutional investors (QFIs) boosted the figure and bought the most.

Index compiler MSCI Inc., which upgraded Saudi Arabia this year, added Aramco to its emerging-market index last week, spurring buying from passive funds. FTSE Russell and S&P Dow Jones also added the stock outside of regular reviews due to the size of the initial public offering. While foreigners balked at the IPO, citing what they deemed to be an expensive valuation among other concerns, managers tracking benchmarks passively had to purchase Aramco in order to comply with the index changes.

Still, the flows from abroad weren’t enough to sustain the stock price near a peak reached after the listing. Aramco fell 3.5% last week, erasing a third of the gains that followed the world’s biggest IPO. Investors from the six-nation Gulf Cooperation Council, Saudi individuals and Saudi institutions, who were key for the IPO to happen, were net sellers last week, data from the exchange showed.

Investors should now see lower trading volume in Aramco compared with the very early days, said Marie Salem, the head of institutions at Daman Securities. “MSCI inclusion did not actually reflect the inflows that we and analysts were expecting. We should still see some sort of inflows that is going to come at a later stage from foreigners in particular.”