21深度｜美国“AAA时代”落幕：“财政悬崖”迫近 美债旧伤未愈再添新愁

Core Viewpoint - The recent downgrades of the U.S. sovereign credit rating by major rating agencies highlight the growing concerns over the sustainability of U.S. fiscal policy and the looming "fiscal cliff" that could have severe implications for the economy and global financial markets [1][2][10]. Group 1: Credit Rating Downgrades - In May 2025, Moody's downgraded the U.S. sovereign credit rating from AAA to AA1, citing increased government debt and rising interest payment ratios [1]. - Fitch downgraded the U.S. long-term foreign currency issuer default rating from AAA to AA+ in August 2023, attributing it to the frequent deadlock in debt ceiling negotiations [2]. - The cumulative downgrades by S&P, Fitch, and Moody's signify the end of the "AAA era" for the U.S. [2]. Group 2: Fiscal Challenges - The U.S. public debt-to-GDP ratio is projected to approach 130% in 2024, raising concerns about fiscal sustainability [2]. - The U.S. budget deficit has consistently exceeded 6% of GDP over the past two years, with projections of 6.4% for the 2024 fiscal year [5]. - The U.S. Treasury reported a fiscal deficit exceeding $1.3 trillion in the first half of the 2025 fiscal year, marking the second-highest half-year deficit in history [5]. Group 3: Market Reactions - Following the downgrade by Moody's, U.S. Treasury yields rose significantly, with the 10-year yield surpassing 4.5% and the 30-year yield exceeding 5% [3]. - The market's response to the downgrades has evolved; unlike in 2011, when a downgrade led to a flight to safety in U.S. Treasuries, the recent downgrades have resulted in increased yields, indicating a loss of confidence in the "safe haven" status of U.S. debt [4][10]. Group 4: Legislative Developments - The "One Big Beautiful Tax Cut" bill, which aimed to reduce taxes and adjust healthcare spending, faced significant political hurdles, reflecting ongoing partisan divisions over fiscal policy [6][7]. - The bill's passage through the House Budget Committee was contentious, highlighting the challenges in reaching a consensus on fiscal reforms [6][7]. Group 5: Long-term Implications - Analysts warn that the U.S. government's debt burden could escalate dramatically, with projections indicating that the debt-to-GDP ratio could reach 200% by 2055 if current trends continue [9]. - The potential for a "fiscal cliff" looms as political polarization hampers effective governance, raising fears of an unsustainable fiscal trajectory [11].