沪指盘中重回4000点，这个板块暴涨13%！发生了什么？

Market Performance - The A-share market opened strongly on January 5, with the Shanghai Composite Index returning to the 4000-point mark after 34 trading days, closing up 1.07% [2][3] - The Shenzhen Component Index rose by 1.87%, and the ChiNext Index increased by 2.15% [2] - Over 4000 stocks in the market rose, with 98 stocks hitting the daily limit [2] Sector Performance - The brain-computer interface (BCI) sector saw a significant surge, with a half-day increase of 13.06%, leading the market [11] - Other sectors that performed well included medical devices, hyperbaric oxygen chambers, and insurance [11][12] - The A500 ETF saw a trading volume exceeding 110 billion yuan, indicating strong institutional interest [9] Investment Trends - Institutional funds have shown significant net inflows into stock ETFs since December, particularly into A500-related ETFs, indicating a bullish sentiment for the upcoming spring market [9] - The stability of the RMB exchange rate has attracted foreign capital back to A-shares and Hong Kong stocks, suggesting a new round of asset revaluation [9] - The ETF market, valued at 6 trillion yuan, is drawing increasing competition from various institutions, which may lead to product innovation and market development [9] Brain-Computer Interface Sector - The BCI sector is experiencing a pivotal moment with multiple catalysts, including Elon Musk's announcement of large-scale production of BCI devices by Neuralink in 2026 [14] - Domestic policies are increasingly supportive, with the National Medical Products Administration accelerating the review process for BCI medical devices [15] - The BCI market is expected to expand significantly due to ongoing technological advancements and supportive government policies, with a focus on clinical applications and consumer scenarios [15]