The most the Fed has ever held on its balance sheet is $5.8T.
Maybe I missed a zero somewhere but China's sale of 10% of their holdings seems in isolation like an awfully manageable problem. A different discussion if there were a ton of other crazy stuff going on in the world economy and they just piled on, perhaps.
US 10y bond auctions are often >40bn in size, with shorter maturities well over that. The seller of this debt (China) wouldn't want to smash the market because they'd only be shooting themselves in the foot.
Point being that it's an easily digestible amount of debt.
I'm sure you also realize that when a large holder sells a significant stake of any asset, traders anticipate they will sell more in the future.
Example 1: Berkshire Hathaway selling $47 million of BYD and the market price dropping 8% the next day, wiping out $10 billion of market value.
Example 2: Musk selling 0.6% of his stake in Tesla, and the market price dropping 15% the next day, wiping out $187 billion in market value.
Example 3: UK government announcing a planned sale of 0.3% of above-ground gold, and the global gold price plunging 10% before the first auction.
How much do they control? Please cite your sources.
I can find some information about "shadow holdings" (exciting!) held in Luxembourg and Belgium [0] but I cannot imagine those treasuries would add up to a multiple of what's officially on the books and held by the Chinese government and Chinese companies. Interesting thought, though.
[0] https://www.cnbc.com/2026/05/19/central-banks-offload-us-tre...