S&P 500 Closes at Record 7,799; Iran Blockade 'Indefinite'

The S&P 500 closed at a record 7,798.99 on Thursday, notching an all-time intraday high above 7,800. The Nasdaq Composite added 0.81%. The rally came after Defense Secretary Pete Hegseth said the U.S. Navy can maintain the blockade of Iranian ports "indefinitely," rotating warships in and out as needed.

Markets often climb a wall of worry. On Thursday, they climbed a naval blockade.

Brent crude for October delivery fell more than 2% to settle at $87.07 a barrel. U.S. West Texas Intermediate dropped to $81.25. Both were marginally higher in early Asia trading Friday. Hegseth's statement, made in Panama, signaled no end date for the operation.

The U.K. economy grew 0.4% in the second quarter after 0.6% in the first, keeping it on track to be the G7's fastest-growing economy for a second straight quarter. Deutsche Bank chief U.K. economist Sanjay Raja called the first-half annualized pace of 2% "scorching." The IMF had warned in April that the Iran war would damage Britain's growth more than any other rich country's, because of its reliance on oil and gas imports. Pump prices are already eating into household incomes.

In Asia, the Kospi entered a technical bull market Thursday, rebounding more than 20% from its July 30 low. The rout last month was driven partly by leveraged positions and forced selling. "Korea's equity market is basically synonymous with the AI hardware trade at this point," said Phillip Wool, head of research at Rayliant Global Advisors. The speed of the rebound shows the volatility in tech stocks, Wool said.

SK Hynix, the world's leading maker of high-bandwidth memory, is investing $720 billion in what it says will be the largest network of memory factories in the world. Its market cap has jumped more than fivefold in the past year, topping $1 trillion. The buildout is a bet that extreme demand from artificial intelligence is here to stay. NVDA, a key customer, is willing to take on more risk to secure supply, the company said.

Investor meetings and executive departures dominated AI news this week. Anthropic CFO Krishna Rao is leading early meetings with prospective investors ahead of a potential IPO, though the conversations haven't covered financials or a valuation, sources told CNBC. The company filed confidentially for its IPO in June after a May round valued it at $965 billion. OpenAI lost chief revenue officer Denise Dresser after eight months, days after longtime executive Brad Lightcap announced his exit. Meta open-sourced its most powerful model, with CEO Mark Zuckerberg arguing that concentrating AI in a few hands is "inherently problematic."

Tim Cook spent Thursday cutting a ribbon in Houston with Commerce Secretary Howard Lutnick at a plant that has already shipped its first AI servers.

The S&P 500 is on track for its third straight weekly advance.