The world’s best-performing new listing this year is a Hong Kong civil-engineering stock soaring for reasons that appear unrelated to its business.

Luen Wong Group Holdings Ltd. jumped 1,438 percent on the first trading day after its April initial public offering and is now 6,715 percent above its offer price. The company, which reported sales of $41 million last year and profit of $1.1 million from projects like laying roads and digging sewers, is today worth $2.9 billion.

The run-up highlights quirks in Hong Kong’s stock market, where wild swings are a regular occurrence, many firms have a tiny portion of their shares available to trade and there’s a healthy sideline in mainland Chinese firms buying companies to engineer reverse takeovers. Luen Wong’s world-beating showing has been ascribed to a combination of all three and has left analysts urging caution.

“My advice for small retail investors is to stay away,” said  Francis Lun, chief executive officer of local brokerage Geo Securities Ltd.

Luen Wong closed down 3.6 percent on Wednesday. The stock’s performance since its debut is a story that Hong Kong has seen fairly often in recent years. A study by the Securities and Futures Commission found that between 2013 and 2015, 56 companies saw their market value jump more than 1,000 percent in a six-month period, even though 39 of them were losing money.

A Luen Wong official answered the phone and requested questions be e-mailed. The firm didn’t respond to the e-mail seeking comment. Henry Yau, an official at the IPO’s sponsor TC Capital Asia Ltd., said his firm wasn’t in a position to comment on share price moves. TC Capital only assisted the company with preparing its listing application and didn’t act as a bookrunner to bring in investors, Yau said in an e-mailed response to questions. Representatives at joint bookrunners Gransing Securities Co. and Suncorp Securities Ltd. didn’t reply to e-mails seeking comment.

Volatility on the small-company exchange where Luen Wong is listed, known as the Growth Enterprise Market, is an issue for bourse operator Hong Kong Exchanges & Clearing Ltd., according to David Graham, the chief regulatory officer and head of the listing division, who was speaking generally. HKEX is working with the SFC to address the matter, he said in a June interview.

In a speech in June, SFC Chief Executive Officer Ashley Alder said the regulator and HKEX were working on a thorough review of GEM and issues surrounding the companies that list there.

“Newly-listed GEM companies are often associated with extreme price fluctuations, small public floats and high shareholding concentrations,” Alder said. “It goes without saying that we have been very concerned about these and other developments in our listed market.”

Ernest Kong, a spokesman for the SFC, declined to comment.