The Rundown — September 23, 2026

What's going on right now, in one place. The ↗ links out to the original source; the item's own text turns into a link only once it becomes a full entry here.

World

President Trump tells the UN General Assembly on September 22 he faces a "big decision" on Iran — a deal or "annihilate the Islamic Republic" — and predicts an agreement only after November's midterm elections, since Tehran is "waiting to see how I do."
Chinese President Xi Jinping arrives in Washington on September 23 for his first U.S. state visit in 11 years, with Thursday's main meeting expected to center on extending last year's trade truce alongside AI, Taiwan and critical minerals.
Ukrainian President Volodymyr Zelenskyy calls on September 23 for a trilateral meeting with Presidents Trump and Putin and repeats Kyiv's readiness for a mutual "energy ceasefire" if Russian strikes on power infrastructure stop.

Business & markets

The Nasdaq 100 closes at a record on September 22, its first since June, as the Philadelphia Semiconductor Index jumps 4.3% and Intel and Arm Holdings both surge more than 12%, while the S&P 500 finishes flat and the Dow falls 0.4%.
Asian equities extend a rally into a sixth straight session on September 23 — India's Sensex opens up more than 100 points and MSCI's Asia Pacific index adds 0.3% — tracking Wall Street's chip rally and falling oil prices tied to hopes for an Iran deal.

Bitcoin & crypto

Bitcoin and ether open near eight-month highs on September 23, with Fundstrat's Sean Farrell declaring "the crypto winter is over" after bitcoin gained more than 5% Friday and another 6% Monday.
BitMEX permanently shuts down at 04:00 UTC on September 23 after 11 years, closing an exchange whose daily volume had shrunk to roughly $400,000 following its 2020 Bank Secrecy Act case and years of losing share to Binance, Bybit and OKX.

Technology

Alibaba unveils its Zhenwu V900 AI accelerator on September 22 at its Hangzhou conference, calling it China's most powerful chip yet, built for clusters of up to 500,000 units and said to triple the performance of its predecessor, days ahead of Xi's Washington visit. Read the entry
House Select Committee on China chairman John Moolenaar urges the Trump administration on September 18 to close "cloud services loopholes" and tighten chipmaking-equipment export controls to China, in a letter sent less than a week before Xi's September 24 Washington visit. Read the entry

Science & space

ESA's JUICE spacecraft swings within 8,640 km of Earth on September…
A paper led by Kenji Furuya of Japan's RIKEN institute finds interstellar object 3I/ATLAS's water carries a deuterium-to-hydrogen ratio of about 1%, tens of times higher than a typical solar-system comet's 0.015%-0.03%, consistent with it forming in a low-metallicity stellar nursery. Read the entry

Health & medicine

A BMJ review of 69 randomized trials covering 153,902 adults finds …
A WEHI-led study of roughly 900 human gut biopsies, published in Science, finds intestinal cells in inflammatory bowel disease patients can stay primed to die even during symptom-free remission, with higher cell-death signaling tied to greater relapse risk over more than two years of follow-up. Read the entry

First published on the Notebook, September 23, 2026.