Net foreign assets at Saudi Arabian Monetary Agency (SAMA) declined 3.1 percent in December from the previous month to SR2.283 trillion ($609 billion), the central bank announced.
Assets dropped 15.9 percent from a year earlier to their lowest level since August 2012. They reached a record high of $737 billion in August 2014 before starting to shrink.
The central bank, which acts as Saudi Arabia’s sovereign wealth fund, has been drawing down its assets to cover a huge state budget deficit caused by a plunge in oil prices.
The bulk of foreign assets are believed to be denominated in US dollars. 
They are mainly securities such as US Treasury bonds and deposits with banks abroad; equities are believed to account for only a small fraction, perhaps less than 20 percent. Some of the assets are managed through major global fund firms.
The December data showed Saudi Arabia accelerating its sales of foreign securities; those holdings shrank 5.5 percent from the previous month to $401 billion in December.
Foreign bank deposits rose 2.8 percent to $147 billion, suggesting Saudi Arabia was setting aside more cash for future use in paying its bills.

Source :Arab News