Trump Tariff Pause
Impact
SPX +9.5% — largest daily gain since 2008
What happened
At 1:18 pm Eastern on April 9, 2025, President Trump posted on Truth Social that he was pausing most reciprocal tariffs for 90 days. AI trading systems reading Truth Social detected and executed on the post within milliseconds. By the time the news wire services ran the headline, the S&P 500 had already moved up roughly 4 percent. It closed up 9.5 percent, the largest single-day gain since the 2008 crisis.
Context
Trump posted the tariff pause on Truth Social at 1:18pm ET. AI trading systems detected and executed within milliseconds. The SPX had already moved +4% before most retail traders saw the headline.
Era
06 · AI Algos & Nanosecond Execution
AI systems scrape Truth Social, X, newswires and execute trades in nanoseconds. The information-to-execution loop is now entirely non-human.
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