Police are urging the public to exercise extreme caution when investing online, saying scams are becoming increasingly sophisticated amid a sharp rise in cases in the first half of 2025.

One recent tactic the force has observed involves scammers responding to online property rental ads posing as wealthy potential tenants. They then develop a relationship with the landlord before duping them into making fraudulent investments and making off with their money.

Overall, the force recorded 16,262 technology-related crimes between January and June, with losses totalling HK$3.05 billion, a 14.7 percent uptick from the same period last year.

About one in seven, or 2,273 cases, involved online investment fraud, representing a 24.8 percent jump year on year. Victims were swindled out of HK$1.48 billion, a surge of 36.4 percent from 2024.

Senior superintendent Carmen Leung from the Cyber Security and Technology Crime Bureau said scammers primarily targeted victims through popular messaging apps and social media platforms.

WhatsApp remained the means of communication, with 1,260 cases linked to the app. That's compared to 411 cases on Facebook, and 226 on Instagram.

Leung added fraudsters would pose as legitimate financial advisers and lure individuals with promises of high returns from stocks, funds and virtual currencies.

Data showed that older individuals were more susceptible to scams - over 70 percent of victims were aged 41 or above.

The largest case so far this year, Leung revealed, involved a 65-year-old retiree who lost over HK$30 million of savings.

The victim came across a post on Facebook claiming to offer investment tips, before joining a WhatsApp group and lured into investing in local and US stocks on bogus trading apps.

"Be cautious that if you are suddenly added to some unfamiliar chat group or contact by some stranger using different pretexts or pretending to [have] some tips," said Leung.

"Do not trust investment advertisement on social media, please do some research before you really do the investment.

"Never download some apps from unverified sources, and watch out for schemes that promise unrealistically high returns."

Police said they are collaborating with social media operators to identify and remove fraudulent content.

One key partner is Meta, the parent company of Facebook, Instagram and WhatsApp.

"We adopt a multi-pronged approach to combat scams, so for example, we built a platform defence. We've developed a range of policies and products features to help people, organisations around the globe to stay safe, including some facial recognition technology and also in-app safety settings," said Maggie Tam, Head of Public Policy at Meta Hong Kong.

"Also we help disrupt scammers... our AI, we have some content review system, which is constantly working on detecting fake accounts proactively."

Meta took down over 157 million scam ads globally from Facebook and Instagram last year, and revoked more than 6.8 million WhatsApp accounts linked to scam centres in the first half of 2025.