Stocks fall but Wall Street notches a winning week after several turbulent days

US stocks experienced a rollercoaster of emotions on Friday, November 13, as the market grappled with the turbulence stemming from the AI sector. The S&P 500 managed to close lower by 0.4%, marking its first winning week since October and its biggest weekly gain since August. The Dow Jones Industrial Average, however, managed to eke out a 0.1% gain. The Nasdaq Composite, though dipping by 0.9%, also managed to notch its first weekly gain in five weeks.

The AI industry, with Nvidia at its forefront, had been the primary driver of market gains and swings. The resignation of Nvidia CEO Jensen Huang, amid concerns over national security due to his affair with a Chinese tech executive, sent shockwaves through the market. This led to a market cap loss of over US$600 billion for Nvidia alone. Other heavyweights such as Broadcom and Advanced Micro Devices also saw their shares plunge by 4.8% and 8.8% respectively.

Despite the AI sector's heavy influence on the market, over 60% of the stocks within the S&P 500 rose on Friday. This allowed the broader market to recover and post a 2.5% gain for the week. Microsoft, for instance, managed to rise by 0.2%, while healthcare and financial stocks also saw gains. Eli Lilly and Co. and Visa and Mastercard each closed 1.3% higher.

The market's overall performance was further affected by fluctuations in oil prices and Treasury yields. Brent crude, the international standard, settled at US$95.84 a barrel, after initially jumping early in the day. The yield on the 10-year Treasury rose to 5.15% from 5.10%, while the yield on the two-year Treasury also saw a slight increase to 4.87% from 4.86%.

Inflation, a key concern for the Federal Reserve, continued to be a hot topic. While wholesale inflation cooled slightly last month, it remains very high, currently above 3%. This inflation trend is expected to continue, putting pressure on the Fed to raise interest rates at the upcoming December meeting, with another hike likely in January.