US stocks dropped sharply, with rising borrowing costs, expensive oil, and a bad Walmart report all hitting at once — bad news for investors, though chip stocks held up.

• The Dow fell over 700 points, and the S&P 500 and Nasdaq also slipped.
• The Treasury said it will double the size of its bond buyback program, which spooked investors worried that borrowing costs are heading higher.
• Long-term government bond yields jumped, with the 30-year rate near its highest level in about 20 years.
• Oil rose more than 2% to its highest since late July after Trump said the US will hit Iran with its most damaging economic measures yet.
• Walmart sank 9% — its worst day in more than four years — after sales and profit guidance came in below expectations.

Outlook: Chip stocks are still holding firm, with TSMC's US-listed shares up on the day, but rising yields and the Iran standoff will keep pressure on the broader market.