SEPT 18, 2026 — S&P 500 falls as Treasury yields rise and the index heads for a losing week; $7T triple-witching expiry hits today; yen plunges after the BOJ hike gets muddied by two dissenters.

What changed

US approves a potential $24B fighter-jet sale to Saudi Arabia while voter opposition to war on Iran hits new highs. Treasury also sanctioned a crypto exchange behind Iran's bitcoin tolls on Hormuz ships. Watch oil. Yen plunges after the BOJ hikes but two dissenters upstage the move—FX is treating the hike as less than credible. Dollar/yen is the pressure valve for every rate differential right now. Researchers used Claude to hack ChatGPT, and experts want independent safety evaluators at Anthropic and OpenAI. Bad signal: if model-on-model attacks work, enterprise AI security budgets are about to explode. China rare earth group in talks to buy MP Materials shareholder Shenghe Resources. MP is the US rare-earth champion; any Chinese stake in its cap table is a national-security headache. Watch MP. Crypto stocks extend gains after SEC opens the door to tokenized stock trading. That's a structural bid for exchanges and custodians—and a direct shot at legacy market plumbing. Regulatory gree

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