The fortune of Saudi Arabia’s richest person, Prince Alwaleed bin Talal Al Saud, has dropped to $15.2bn, its lowest level since the Bloomberg billionaires index began tracking him in 2012.

The value of his portfolio of public equities, stakes in closely held companies and Saudi real estate fell $760m in the first three quarters of the year, according to a document from his private office.

The decline was due to "minor adjustments" in the valuation of assets and some disposals, including the recent sale of his stake in US ride-hailing company Lyft to his investment company, Kingdom Holding.

The world’s wealthiest people have, in aggregate, lost 2% of their wealth so far this year, or $103bn, according to the index.

Alwaleed’s most valuable asset, a 95% stake in Kingdom Holding, has dropped 70% of its value since hitting a record high in 2014.

The company’s shares fell more than 20% following Alwaleed’s sudden detention in an anticorruption crackdown in November 2017 and have never fully recovered.

One of dozens of princes, ministers and senior officials held at the Ritz-Carlton, he was released after 83 days and said he signed a "confirmed understanding" with Saudi authorities that left him free to function with "zero conditions".

Earlier this month, Kingdom Holding announced that it was close to signing a $1bn loan, its first borrowing since Alwaleed was detained.

The document from the prince’s office showed an increase in the value of his media company, Rotana, following its August investment in Deezer, a Paris-based music streaming firm.