What Happened to the Stock Market When a Ceasefire Expired
On August 18, 2026, a 60-day ceasefire expired without any agreement to extend it. The result was swift: oil prices went up, and so did Treasury yields (the interest rates the U.S. government pays to borrow money). When yields rise, they tend to pull stock prices down — and that is exactly what happened. Chip stocks fell sharply, and big tech companies led the decline: Microsoft dropped 3.0% and Meta fell 3.5% Saxo. The moves also brought back worries that the Federal Reserve might raise interest rates again in the second half of 2026.
Here is why rising yields hurt tech stocks in particular. When you buy a stock, you are essentially betting on the money the company will make in the future. To figure out what those future earnings are worth today, investors use a discount rate — a percentage that shrinks future dollars to today's value. Treasury yields are a big part of that rate because they are seen as almost risk-free. So when Treasury yields go up, the value of future earnings goes down. Companies like Microsoft and Meta, whose stock prices already reflect high expectations for growth far into the future, feel this pinch the most.
The Treasury publishes these yield numbers every day. They estimate the rates at which the U.S. government could borrow for periods ranging from 3 months to 30 years, using end-of-day market prices and a specific statistical method described in Treasury methodology published in February 2025 U.S. Treasury. The reported maturities include 1, 1.5, 2, 3, 4, and 6 months, and 1, 2, 3, 5, 7, 10, 20, and 30 years U.S. Treasury.
The August 18 yield climb did not happen in isolation. In June 2026, short-term Treasury yields had already risen as investors anticipated possible Fed rate hikes in the second half of the year Breckinridge. Before that, BlackRock's weekly market commentary had pointed in the opposite direction: yields fell because weak jobs data reduced pressure for the Fed to raise rates, though longer-term yields had been rising faster than short-term ones, suggesting inflation worries were not going away BlackRock.
J.P. Morgan Global Research expects yields in developed markets to climb gradually through 2026, with 10-year U.S. Treasury yields reaching 4.35%, 10-year German government bonds (Bunds) reaching 2.75%, and 10-year U.K. government bonds (gilts) reaching 4.75% J.P. Morgan. If the August 18 yield increase holds, it would follow that path rather than break from it.
The chain of events from the ceasefire expiry to the stock selloff is fairly direct. Unresolved geopolitical conflict pushes oil prices up. Higher oil prices feed into inflation expectations — people and markets start worrying that goods and services will cost more. That pushes Treasury yields higher. The steeper yield curve that BlackRock noticed, where long-term yields rise faster than short-term ones, suggests markets are demanding extra return for the risk that inflation stays high for years, not just a few months. The chip stock selloff adds to the picture because semiconductor companies' stock prices tend to swing more dramatically than the overall market when growth expectations or borrowing rates shift.
The Treasury's yield methodology uses bid-side prices, meaning the yields reported reflect what sellers in the bond market were actually able to get at the close of trading. If oil prices keep carrying a geopolitical risk premium — that is, if they stay elevated because the conflict remains unresolved — the gradual yield rise J.P. Morgan projects could arrive sooner than expected.
The bigger picture is a real tug-of-war. Weak jobs data, which had been pushing yields down, argues for the Federal Reserve to be patient and hold rates steady. Rising oil prices and the inflation threat they bring argue for the Fed to start raising rates again. The Fed's decisions in the second half of 2026 will come down to which of those two forces wins out — and that choice will affect mortgage rates, credit card interest, savings returns, and stock prices for ordinary Americans.
