Stocks advanced across the board Wednesday as investors continued to put recent political turmoil in the background, sending the S&P 500 and Nasdaq to new all-time highs while the Dow Jones Industrial Average added modest gains. The S&P 500 climbed roughly 0.9 percent to close near 5,245, the Nasdaq Composite rose about 1.2 percent to finish around 17,980 and the Dow gained 0.6 percent, adding roughly 235 points to settle near 39,850. Volatility remained subdued and breadth favored large-cap technology names.

Nvidia led the market’s biggest names higher after the chipmaker and OpenAI disclosed an expanded partnership that investors interpreted as a revenue catalyst for Nvidia’s data-center business. Nvidia shares jumped more than 6 percent in regular trading, a move that analysts estimated contributed about 20 to 25 basis points to the S&P 500’s advance. “This is a classic earnings-and-expectations story — AI-related demand is still the key growth narrative investors want exposure to,” said Erik Larson, chief market strategist at Meridian Capital. “That dynamic is outweighing short-term political noise.”

The rally followed a string of strong sessions for equities: the S&P has posted several record closes in recent weeks and recorded a fifth consecutive monthly gain in September, while the Nasdaq has also posted multi-week advances. Investors cited a combination of factors supporting risk assets: a Federal Reserve move earlier in the month to cut interest rates, signs of resilient consumer spending, and upbeat corporate guidance from several large technology firms.

Fixed-income markets were largely steady, with the 10-year Treasury yield edging down to about 4.20 percent from roughly 4.25 percent a day earlier, reflecting the market’s view that any shutdown will be short-lived and that policymakers still retain the flexibility to respond if growth falters. Trading volumes on the New York Stock Exchange were light relative to recent averages, suggesting a cautious participation underpinning the gains.

The partial government shutdown entered its second day after Congress failed to pass a continuing resolution late last week, shuttering some federal operations and raising concerns about furloughs and delayed services. Economists caution the economic cost depends heavily on duration. “A brief shutdown typically trims a few tenths of a percentage point from quarterly GDP, but a prolonged impasse could dent confidence, procurement and payrolls in ways markets would eventually reprice,” said Dr. Michelle Park, senior economist at Beacon Economics.

For now, investors appear to be pricing in a short disruption rather than a systemic shock. Still, strategists warned that sentiment could shift quickly if the shutdown persists or if corporate earnings disappoint. “Market internals are healthy, but policy risk is a live factor,” said Larson. “The next big market move will likely hinge on whether lawmakers deliver a quick resolution or the impasse drags on into October.”