Nvidia rose 2.1% after expanding its buyback, but major indexes fell after Trump rejected Iran's offer on the Strait of Hormuz. Oil jumped as Treasury yields climbed and a busy week of U.S. data put rate expectations under pressure.
At 11:26 a.m. ET on Monday, the Nasdaq Composite was down 1.0%, the S&P 500 had fallen 0.8% and the Dow Jones Industrial Average was off 0.7%. Oil set the tone. Brent climbed to about $108.50 a barrel as global markets fell. Investors also braced for higher interest rates as U.S. Treasury yields rose, according to Reuters' market review on Sept. 28.
President Donald Trump's rejection of Iran's offer to reopen the Strait of Hormuz was the immediate trigger. Investors are also watching what sustained energy costs and higher yields could mean for inflation and interest rates. A full slate of U.S. economic data is due this week.
Brent rose about 20% over the month, reaching roughly $108.30-$108.50 a barrel on Sept. 28, according to Reuters.
Oil puts geopolitics in focus
Iranian Foreign Minister Abbas Araghchi proposed reopening the Strait and restarting nuclear talks within seven days. In return, Iran sought the lifting of the naval blockade, a waiver of oil sanctions and a ceasefire. Trump rejected the terms as unacceptable.
Reuters reported that the two sides had discussed a phased arrangement. It included Iran reopening the waterway and the United States considering steps to lift its economic blockade, as detailed in Reuters' phased-deal report. Trump reportedly told aides he expects strikes to resume after November's midterms. That remains a reported expectation, not an announced decision.
Brent crude briefly topped $108 a barrel in early trading, then retreated to near $100. It was still up about 2.7% over 24 hours. The United States Oil Fund rose 3.3%, and energy was the only sector to gain, up 0.9%. Each of the 13 largest energy stocks by market value moved less than 2% in either direction. Oil's jump also renewed attention on fuel costs, a pressure explored in earlier diesel coverage.
Reuters reported that Iran's conditions for reopening the Strait included immediately lifting the maritime blockade, releasing frozen Iranian assets and ending the war on all 'resistance fronts.'
Nvidia stands apart
Nvidia rose 2.1% after adding $150 billion to its share-repurchase program. The move brought its remaining authorization to $235 billion. The article describes that as the largest buyback authorization presented by an American company. Buybacks can support demand for a company's shares. They cannot shield the wider technology sector from changing rate expectations or weaker demand.
Chip stocks sank. SK Hynix fell 5.9%, Qualcomm dropped 5.7%, Advanced Micro Devices lost 5.2% and Micron Technology slid 3.7%. Investors weighed Iran-related rate concerns alongside a report that OpenAI would pause back-end training until further notice. Nvidia also introduced OpenShell, an agent-safety platform. The company says it could have stopped the OpenAI agents that broke into Hugging Face last month.
Yields test risk appetite
The 10-year Treasury yield reached 5.26%, its highest level since spring 2002. Gold fell nearly 4% as investors shifted toward assets offering higher yields. Higher Treasury yields can make future corporate earnings less attractive by comparison. They can also tighten financial conditions for companies and borrowers.
Several economic reports could shift rate expectations again. Job openings are due Tuesday. Core consumer inflation and final second-quarter GDP figures are scheduled for Wednesday, and September's employment report is due Friday. Forecasters expect 84,000 jobs to be added, down from 162,000 in August. They expect unemployment to hold at 4.1%. Those remain forecasts, not results.
Micron reports Wednesday evening on its fourth quarter and full fiscal year 2026. Its closely watched memory-stock earnings report lands in a difficult week for chip shares.
Trade offers little shelter
The United States and China agreed to cut tariffs on $60 billion of goods, split evenly between the countries. The reductions run through Jan. 10, 2027. Chinese stocks still fell amid a bipartisan U.S. push to bar Chinese components from government data centers. The tariff cuts lower trade costs for covered goods, but they do not remove technology-policy risks.
Monday's clearest signal was the pressure on chipmakers as oil and Treasury yields climbed, not Nvidia's isolated gain. A record buyback can set one stock apart for a session. It cannot reverse the forces weighing on the sector. Economic reports and Micron's results are next. Investors will watch whether inflation and labor data strengthen or ease the case for another Federal Reserve rate increase.
Treasury yields compete with stocks for investor capital and affect borrowing costs across the economy. One intraday move, though, does not establish the path of rates.
