Changes media identifier to HONGKONG-LISTING/MOMENTA. Previously HONGKONG-IPO/MOMENTA. Adds details and quotes throughout

By Yantoultra Ngui and Jiaxing Li

SINGAPORE/HONG KONG, July 8 (Reuters) - Shares of Momenta Global 6880.HK debuted flat in Hong Kong on Wednesday, after the Chinese autonomous-driving firm raised about HK$5.89 billion ($751 million) in its initial public offering.

The stock opened at HK$301 versus its IPO price of HK$295.60, reaching as high as HK$314.80 before trading at the HK$299 level.

Momenta's debut is a key test of investor demand for Chinese AI and advanced technology companies, as Hong Kong faces a record wave of lock-up expirations after a strong first-half for new listings.

"July's peak unlocking period is clearly weighing on things, some new listings aren't performing as expected, so the market sentiment has cooled noticeably," said Dickie Wong, executive director ​of research at Hong Kong-based uSMART.

"Investors seem more selective on valuations right now, especially in AI or tech."

Cornerstone investors, or big investors that committed to buy shares before listing, included existing backer Mercedes-Benz MBGn.DE, BlackRock BLK.N funds and China's Boyu Capital, according to the prospectus.

Other cornerstone investors include GIC, Fidelity International, Oaktree, Franklin Templeton and ChinaAMC.

That lineup of cornerstone investors and pricing at the top end of the offer range showed decent global investor appetite for China's AI story, said Gary Ng, senior economist for Asia Pacific at Natixis CIB.

"Still, the lack of a sharp surge suggests sentiment remains cautious with a focus on long-term opportunities, unlike the global AI hype," Ng said.

"There can be pressure on valuation in the tech sector. Whether these firms can hold up after listing is key to watch, which may not always be the case for previous cases."

Other Hong Kong debutants on Wednesday also had a mixed start. Visual AI firm Reconova 7656.HK opened 16.9% lower, while mining autonomous-driving firm Eacon 7687.HK started trading 3.5% higher.

Trench-cover maker Baogai 8090.HK opened flat, while silicon carbide chip maker BasicSemi 9971.HK opened 7.9% higher.

Founded in 2016 by former Microsoft MSFT.O researcher Cao Xudong, Momenta sells driving-assistance software to automakers. The systems help cars steer, brake, change lanes and park, but drivers still need to stay alert and ready to take control.

Momenta plans to use about 60% of the IPO proceeds for research and development, 20% for robotaxi services, 10% for its mass-produced vehicle business and 10% for working capital.

The company said in the prospectus that vehicles using its software had topped 680,000 by the end of 2025. Its customers and partners include Toyota 7203.T, Mercedes-Benz, SAIC Motor 600104.SS, General Motors GM.N, BYD 002594.SZ and Audi.

($1 = 7.8421 Hong Kong dollars)