深夜，暴跌！

Group 1: Cryptocurrency Market Overview - The cryptocurrency market is experiencing significant sell-offs, with Bitcoin dropping below $84,000 and a decline of over 6%, while Ethereum fell more than 8% [3]. - Analysts indicate that December marks a cooling of risk appetite, with limited inflows into Bitcoin spot ETFs and a lack of buying interest at lower prices [4]. - The downgrade of the global largest stablecoin USDT by S&P Global Ratings has added pressure to the cryptocurrency market, warning of potential collateral shortfalls if Bitcoin prices decline [4][5]. Group 2: Impact on Stock Market - The decline in Bitcoin is expected to pose substantial issues for the stock market, as the performance of crypto assets is largely dependent on net liquidity [5]. - Major U.S. stock indices have seen declines, reflecting the broader market's cautious sentiment amid the cryptocurrency sell-off [5]. Group 3: Nvidia's Investment in Synopsys - Nvidia has invested $2 billion in Synopsys, purchasing shares at $414.79 each, as part of a collaboration in engineering and design [8][9]. - Following the announcement, Synopsys shares rose approximately 8%, despite a nearly 14% decline year-to-date [9][10]. - Nvidia's investments in various companies, including Synopsys, have raised concerns about potential "circular trading," where increased valuations lead to further purchases of Nvidia's chips by these companies [9].