Here is a look at the companies that are making news during midday trading:

- **CoreWeave**: Shares of this cloud services provider dropped over 7% in their second trading session following its public debut. CoreWeave, which leases Nvidia graphics processing units to major tech firms, experienced a disappointing launch last week. Nvidia’s stock also fell by more than 4% on Monday.

- **Canada Goose**: The Canadian outerwear brand saw its stock decrease by over 3%, reaching a new 52-week low after Barclays downgraded it to "underweight" from "equal weight." The downgrade was attributed to global economic pressures, intensifying competition, and possible tariff repercussions.

- **Moderna**: The biotech company’s shares plummeted 8.9% after the resignation of Peter Marks, the top vaccine regulator at the U.S. Food and Drug Administration. Marks cited "misinformation and lies" regarding vaccinations for his departure, raising concerns about the potential for expedited approvals of essential vaccines by the Trump administration.

- **Celsius Holdings**: The energy drink maker's stock rose approximately 5.9% following Truist's upgrade from "hold" to "buy." Truist indicated that investors are already looking past challenges projected for 2024 and early 2025, focusing instead on the benefits of the Alani Nu acquisition, which could enhance the company’s positioning in the U.S. energy drink market, particularly among women.

- **Tesla**: The electric vehicle manufacturer saw a price drop of over 1% after Stifel reduced its price target, citing a slower than anticipated rollout of the new Model Y and recent protests that could pressure short-term sales. Year-to-date, Tesla’s shares have underperformed the broader market, down more than 36%.

- **Crypto Stocks**: Stocks tied to Bitcoin declined as the leading cryptocurrency's prices fell over the weekend. Coinbase and Robinhood, both exchange platforms, saw declines of approximately 1% and 0.7%, respectively, while crypto miner Mara Holdings dropped by 7.8%.

- **Palantir Technologies**: The defense tech firm's shares fell by 1.7%, marking its fifth consecutive losing session. Last week, Palantir's stock had already dropped over 5%.

- **United Airlines**: The airline’s stock declined by 1.7% on Monday, putting it on track for its worst month since March 2020, with shares down 27% month-to-date. Competitors American Airlines and Delta Air Lines are also experiencing similar declines, both nearly down 30% for the month.

- **Mr. Cooper Group**: This mortgage services provider's shares surged 14.5% after fintech platform Rocket Companies announced a definitive agreement to acquire the firm in an all-stock deal valued at $9.4 billion, expected to close in the fourth quarter of 2025. Shares of Rocket Companies fell about 9%.

— Reports contributed by CNBC's Sean Conlon, Yun Li, Alex Harring, Michelle Fox, and Lisa Han.

In midday trading, several companies made notable headlines due to significant movements in their stock prices, reflecting a mix of corporate developments and broader market trends.

CoreWeave experienced a notable drop, with shares declining over 7% in its second trading session following its disappointing public debut. The cloud provider specializes in renting out access to Nvidia's graphics processing units (GPUs) for large tech firms. This downturn also affected Nvidia, which saw its shares decrease by more than 4%, signaling investor concerns adjacent to CoreWeave's struggles.

In another development, Canada Goose, the Canadian outerwear brand, saw its stock price fall over 3% to a new 52-week low after Barclays downgraded its rating from equal weight to underweight. The downgrade was attributed to various factors including global macroeconomic pressures, heightened competition, and potential impacts from tariff exposure.

Moderna, a key player in the biotech sector, faced a significant decline with an 8.9% drop in its shares following the resignation of Peter Marks, the top vaccine regulator at the U.S. Food and Drug Administration (FDA). Marks cited "misinformation and lies" surrounding immunization as a reason for his exit, raising concerns over the potential impact on the swift approval and promotion of critical vaccines by the Biden administration.

On a more positive note, Celsius Holdings, an energy drink manufacturer, saw its stock rise by approximately 5.9% after Truist upgraded its rating from hold to buy. The investment firm noted that the market is optimistic despite foreseeable challenges into 2024 and Q1 of 2025, particularly focusing on the advantages derived from Celsius's acquisition of Alani Nu and its potential to appeal to women in the U.S. energy drink market.

Tesla's stock also felt pressure, declining by more than 1%. Stifel adjusted its price target downward, highlighting a slower-than-anticipated rollout of Tesla's Model Y and recent protests, which are contributing factors that might pressure sales in the short term. The electric vehicle manufacturer has faced a challenging year, with its shares down over 36% since the beginning of the year.

In the cryptocurrency sector, stocks related to Bitcoin fell as the cryptocurrency itself experienced a price drop over the weekend. Companies like Coinbase and Robinhood saw their shares decline by approximately 1% and 0.7%, respectively, while crypto miner Mara Holdings suffered a larger loss of 7.8%.

Palantir Technologies faced a similar fate, with its shares down 1.7%, marking its fifth consecutive day of losses after a prior decline of more than 5% the previous week.

United Airlines saw a 1.7% decline in its stock price, contributing to a notably poor performance this month. The airline's shares have dropped around 27% month-to-date, marking its worst month since March 2020. Competitors American Airlines and Delta Air Lines are experiencing similar declines, with each down nearly 30% for the month.

On the contrary, Mr. Cooper Group, a mortgage services lender, enjoyed a significant stock boost, climbing 14.5% after it was announced that fintech platform Rocket Companies had reached a definitive agreement to acquire Mr. Cooper Group. The all-stock transaction is valued at approximately $9.4 billion and is anticipated to close in the fourth quarter of 2025. Conversely, shares of Rocket Companies saw a decline of about 9%.

Overall, the midday trading session encapsulated a mix of caution and optimism, with various companies experiencing significant shifts in their stock performances based on news, market sentiment, and industry trends.