US stocks came under pressure on August 18 as Treasury yields climbed and oil prices stayed elevated, weighing especially on semiconductor shares. The 10-year Treasury yield rose about 2 basis points to 4.75%, its highest level in 19 months, while the 30-year yield briefly neared 5.33%, the highest in more than two decades. By 10 a.m. in New York, the S&P 500 was down 0.4%, the Nasdaq Composite had fallen 1.1%, and the Dow Jones Industrial Average slipped 0.1%. Chip stocks reversed from the prior session's gains, sending the Philadelphia Semiconductor Index down more than 5%, with Nvidia, Micron, SanDisk, SK Hynix ADRs, Intel and AMD all trading lower. Oil added to the pressure as US West Texas Intermediate crude futures traded above $85 a barrel and Brent crude futures rose past $91 amid deadlocked talks between Iran and the US. Investors are watching whether persistent energy prices feed through to inflation and keep long-term borrowing costs high. Even so, rate swaps tracked by CME Group's FedWatch tool still implied a 63% chance that the Federal Reserve leaves rates unchanged in September, versus a 37% chance of an increase, after recent data pointed to a cooler US labor market and slower inflation.