Singapore shares tanked on Thursday after US President Donald Trump imposed a base rate of 10% tariff on Singapore while upping tariff on its largest trading partner, China, to 54% as key trading partners brace for a fresh batch of economic challenges.

The Straits Times Index (STI), a key benchmark for the Singapore Exchange, ranged between 3,902.98 and 3,955.04 throughout the day. It ended the session at 3,942.23, down 11.98 points or 0.3% compared to Wednesday's close.

In economic news, Singapore's Manufacturing PMI fell to 50.6 in March from 50.7 in February, the lowest in eight months, according to data from the Singapore Institute of Purchasing & Materials Management.

Meanwhile, Singapore's private sector activity rose at the sharpest rate in four months in March, according to the latest S&P Global Singapore Purchasing Managers' Index survey.

In company news, shares of King Wan were up nearly 6% after the company secured mechanical and electrical contracts worth around SG$40.4 million between January and March.

CreditBureauAsia's was down over 1% at the close after its subsidiary, Credit Bureau (Singapore) was granted a license by the Monetary Authority of Singapore to carry out a consumer credit reporting business.

Meanwhile, Oiltek received an in-principal approval from the SGX to transfer to the mainboard.

STI fell 0.3%; Nio, Yangzijiang Shipbuilding fell 4%; SATS fell 3%; Seatrium fell 2.4%; UOB fell 2%; DBS fell 1%; Singtel up 2.6%.