By Yang Jie and Sherry Qin
Shares of a Chinese chip assembler soared almost four-fold in its first day of trading in Shanghai, reflecting strong investor appetite for companies that can help power Beijing's AI ambitions.
SJ Semiconductor's stock rose as high as 100.99 yuan on Tuesday, putting its market valuation at over $20 billion after it raised about $740 million in mainland China's biggest initial public offering so far this year.
The debut by Jiangsu-based SJS, which specializes in chip packaging and testing, is the latest in a wave of chip and AI listings in China and Hong Kong as companies tap public markets to fund growth amid intensifying competition and China's push for tech self-sufficiency.
Analysts view SJS's blockbuster IPO as signaling a shift in investor sentiment toward specialized Chinese companies that provide infrastructure for high-end AI chips, and away from traditional, lower-margin semiconductor assembly and testing firms.
Other high-profile listings that have drawn strong investor enthusiasm include AI chip designers Moore Threads, MetaX and Montage Technology.
Like others in China's tech sector, SJS has grappled with U.S. restrictions that limited its access to advanced chip-making equipment and technologies, fueling a shift toward localization that puts it in a good position to benefit from Beijing's drive for technological autonomy.
SJS was founded in 2014 as a joint venture between China's top chip manufacturer, Semiconductor Manufacturing International Corp., and JCET Group. SJS was added to the U.S.'s entity list in 2020, and SMIC sold off its stake in SJS the following year.
Since then, SJS has pivoted toward a strategy of domestic substitution, seeking to bypass reliance on foreign technology by fostering local alternatives.
Taiwan Semiconductor Manufacturing Co. has long been the leading provider of advanced packaging. But the Taiwanese company's capacity constraints, combined with massive AI-driven demand, is opening up room for smaller local providers like SJS.
Advanced chip packaging accounted for more than half of SJS's revenue in the first half of last year, up from about 5% just a few years earlier, company filings show. Its revenue has surged over the past three years--reaching 6.52 billion yuan in 2025, or about $918 million.
It plans to use the proceeds raised in the IPO to expand production capacity for specialized techniques such as combining multiple chip components into one high-performance module.
Shares in SJS finished the day at 76.65 yuan, up about 290%.
Write to Yang Jie at jie.yang@wsj.com and Sherry Qin at sherry.qin@wsj.com
(END) Dow Jones Newswires
April 21, 2026 03:14 ET (07:14 GMT)
Copyright (c) 2026 Dow Jones & Company, Inc.
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