DUBAI- Kuwait Investment Authority (KIA) has sold a 16.1% stake in Gulf Bank to Alghanim Trading Co for 152.93 million dinars ($503 million), making the business conglomerate the biggest shareholder of the country's fourth-biggest bank, according to a bourse filing.

The purchase will almost double the Kuwaiti group's stake to about 33% from a previous level of 16.67%.

Alghanim, which has interests in manufacturing, automotive and food businesses, is controlled by Omar Kutayba Ahmad Alghanim, the chairman of Gulf Bank.

According to Refinitiv Eikon data, KIA owned 20.21% of Gulf Bank before the stake sale, which took place through an auction on Wednesday.

KIA still owns stakes in other banks, including a 24% stake in Kuwait Finance House and a 19.2% stake in Bank of Bahrain and Kuwait.

($1 = 0.3040 Kuwaiti dinars)

(Reporting by Saeed Azhar, editing by Davide Barbuscia) ((Saeed.Azhar@thomsonreuters.com; +971 44536787; Reuters Messaging: saeed.azhar.reuters.com@reuters.net))