On August 21, the three major A-share indices closed higher, with the ChiNext Index leading the gains. The Shanghai Composite Index edged up 0.04% to 3,905.20 points, the Shenzhen Component Index rose 0.87% to 14,094.17 points, the ChiNext Index climbed 1.43% to 3,545.58 points, the STAR 50 Index inched up 0.04% to 1,653.56 points, and the Beijing Stock Exchange 50 Index fell 0.57% to 1,075.38 points. Total trading volume across Shanghai and Shenzhen reached approximately 1.879 trillion yuan, down about 200.1 billion yuan from the previous session.

Market breadth showed 2,505 stocks advancing against 2,862 declining, with 57 hitting the daily limit up and 14 hitting the daily limit down, meaning advancing stocks accounted for roughly 45% of the market. By sector, precious metals (+4.64%), energy metals (+4.60%), communication equipment (+2.98%), electronic components (+2.80%), and industrial metals (+2.42%) led the gains. On the flip side, crop farming (-4.81%), chemical pharmaceuticals (-4.33%), medical services (-3.75%), biological products (-3.63%), and agricultural product processing (-3.55%) suffered the steepest losses.

Looking at the driving forces behind the session, all three major indices closed in positive territory, with the ChiNext Index up 1.43% to lead the way, while the Shanghai Composite and STAR 50 each gained 0.04%, essentially flat. The Beijing Stock Exchange 50 was the sole decliner at -0.57%. Trading volume stood at about 1.88 trillion yuan, a decrease of roughly 200.1 billion yuan from the prior day.

In the precious metals space, U.S. stocks fell overnight while spot gold surged to $4,543.56 per ounce, hitting a fresh high since June 1. The U.S. Treasury announced on August 19 a significant expansion of its long-dated bond buyback program, and Treasury Secretary Bessent signaled on August 20 that buyback scale could be further increased. This reinforced expectations of lower long-term real interest rates, driving strength in gold and silver stocks.

In the lithium mining sector, the main contract for lithium carbonate on the Guangzhou Futures Exchange peaked at 157,500 yuan per ton, rebounding over 12% from the low earlier this month. Supply and demand for lithium carbonate remain tight, and Rongjie Co., Ltd. posted first-half net profit attributable to shareholders of 1.002 billion yuan, up more than tenfold year-on-year.

In communications, SK Hynix, in collaboration with the University of Virginia, published a research paper on CPO (co-packaged optics) technology in Nature Electronics. Eoptolink Technology disclosed a restricted stock incentive plan on the evening of August 20.

The pharmaceutical sector showed internal divergence, with CanSino Biologics, Jiankai Technology, and Novoprotein all hitting the 20% daily limit for a second consecutive session. The tumor vaccine concept climbed 6.24%, ranking first among concept sectors. However, chemical pharmaceuticals and medical services dragged the broader pharma direction lower.

In the hot sectors, precious metals saw gold and silver stocks strengthen across the board, with the Shenwan precious metals sector up 4.64%, topping the secondary industry rankings. Hunan Silver, Shengda Resources, Baiyin Nonferrous, Shenzhen Zhongjin Lingnan, and Fuda Alloy all hit the daily limit. Chifeng Jilong Gold rose 7.22%, Xiaocheng Technology gained 8.55%, and China Gold International added 5.85%. The catalyst was spot gold reaching $4,543.56 per ounce, a new high since June 1, alongside the U.S. Treasury's expanded long-term bond buyback program and strengthened expectations of lower long-term real rates.

Energy metals saw lithium mining concepts rally collectively, with the Shenwan energy metals sector up 4.60%. Rongjie and *ST Weiling hit the daily limit, while Tianhua New Energy, Shengxin Lithium Energy, and Dazhong Mining followed suit. The driver was the lithium carbonate main contract peaking at 158,500 yuan per ton, rebounding over 12% from the August 3 low, with supply-demand dynamics staying tight and Rongjie's interim net profit up more than tenfold year-on-year.

Communication equipment was active in CPO and optical communications, with the Shenwan sector up 2.98%. Star Net, Tongding Interconnection, Raisecom, and Kechuan Tech hit the daily limit, while Eoptolink rose 6.76% and Zhongji Innolight added 4.29%. The catalyst was SK Hynix's CPO paper in Nature Electronics, plus Eoptolink's restricted stock incentive plan targeting 2026 revenue of no less than 50 billion yuan.

Sectors in decline included crop farming, chemical pharmaceuticals, medical services, biological products, and agricultural product processing, with crop farming down 4.81% and chemical pharmaceuticals off 4.33%. Among individual stocks, Qiule Seed Industry tumbled 15.21%, Luoniushan fell 9.20%, and Harsan and Hayao both hit the daily limit down. These sectors had previously posted substantial gains, and their sharp declines on this day highlight a clear pattern of sector rotation in the market.