1. Supreme Court ruling could affect tariffs and lead to stock market volatility. 2. Potential refunds of up to $140 billion for importers if tariffs are ruled illegal. 3. 10-year Treasury yield at highs not seen since September, signaling market concern. 4. Costco is among companies suing for tariff refunds in light of Supreme Court ruling. 5. Higher borrowing costs and inflation strain households and small businesses.