Today's biggest winners and losers in the stock market, a look at the notable movers: 

On this episode of Stock Movers:

- Nvidia CEO Jensen Huang defended the financial health of CoreWeave (CRWV), saying its strength is improving every day and its cost of capital is decreasing. CoreWeave's shares gained after Huang's remarks, erasing earlier losses, but its bonds were trading at deeply distressed levels and credit-default swaps were pricing in a high chance of default. CoreWeave has a large debt load, with more than $40 billion of debt, and its free cash flow has turned negative, prompting concerns about its viability and contributing to a selloff in stocks globally.

- JB Hunt (JBHT) shares dip 4.7% postmarket after the trucking firm reported third-quarter results, with operating ratio and operating ratio excluding fuel surcharge higher than estimates. 

- Alcoa (AA) posted stronger-than-expected third-quarter results on the strength of higher aluminum production and prices. Adjusted per-share profit of $1.82 was 33 cents above the average estimate of analysts in a Bloomberg survey. Adjusted earnings before interest, taxes, depreciation and amortization almost tripled to $789 million from a year earlier. Shares of Alcoa rose in late trading.