SINGAPORE, Sept. 5 -- Singapore police have warned of a resurgence in "pump and dump" stock manipulation scams, with 21 cases involving overseas-listed companies reported in the past two months.

One case involving a Hong Kong-listed company resulted in losses of more than S$700,000 (RM2.82 million), Singapore-bsed The Straits Times reported police saying in an advisory today.

Scammers typically pose as investment experts or trading mentors on social media and messaging platforms such as WhatsApp, building trust before recommending supposedly high-potential shares listed in Hong Kong or the US.

They then drive up demand and prices through coordinated buying before selling their own holdings at inflated prices, causing the shares to plun...