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- Fitch cut the US's credit rating Tuesday, citing rising debts and an "erosion of governance".
- The downgrade comes two months after Joe Biden and House Republicans reached an 11th-hour deal to stop a catastrophic default.
- Stocks declined after the agency's shock announcement.
August is usually the quietest month of the year for the stock market.
But Fitch shattered any sense of summer calm last night when it slashed the US government's credit score in what could end up being a massive blow to President Joe Biden's economic track record.