According to The Kobeissi Letter, the S&P 500 lost nearly 80 points in just 30 minutes at 1:00 PM ET following a weak 20-year US Treasury bond auction, which triggered a rapid spike in Treasury yields (source: The Kobeissi Letter on Twitter, May 21, 2025). This sharp move in yields spooked equity markets due to concerns over higher borrowing costs and potential shifts in risk appetite. Crypto traders should closely monitor US Treasury yields, as rising yields can lead to risk-off sentiment, impacting Bitcoin and altcoins through capital outflows and increased volatility. The event underscores the interconnectedness between traditional bond markets and crypto assets, making Treasury auction results a key watchpoint for crypto risk management.