CRH, Carvana, And Comfort Systems USA To Join S&P 500

Investing.com -- Carvana Co (NYSE:CVNA) stock surged 9% following the announcement that it will be added to the S&P 500 index as part of the quarterly rebalance, effective prior to market open on December 22, 2025.

S&P Dow Jones Indices revealed that Carvana will join the prestigious index alongside CRH PLC (NYSE:CRH), which jumped 7%, and Comfort Systems USA Inc (NYSE:FIX), which gained 1.8% in after-hours trading on Friday. The three companies will replace LKQ Corporation (NASDAQ:LKQ), Solstice Advanced Materials, and Mohawk Industries Inc (NYSE:MHK), which fell 1.5%, 0.1%, and 0.4% respectively.

The index changes are part of a broader quarterly rebalance that also affects the S&P MidCap 400 and S&P SmallCap 600 indices. UL Solutions Inc (NYSE:ULS) and Pinterest Inc (NYSE:PINS) were among the beneficiaries of the midcap additions, with their stocks rising 3.3% and 4.2% respectively. Booz Allen Hamilton Holding (NYSE:BAH) also gained 4.2% on news of its inclusion in the S&P MidCap 400.

Other companies being added to the MidCap 400 include SPX Technologies, Dycom Industries, Borgwarner, and Hecla Mining Co. Meanwhile, eight companies will be removed from the midcap index, including both classes of Under Armour stock, Power Integrations, Perrigo Company, and Iridium Communications.

The S&P SmallCap 600 will undergo even more significant changes, with 13 additions and 13 deletions. Companies being added to the small-cap index include those removed from the larger indices, plus Primoris Services, Casella Waste Systems, Indivior, and Hawaiian Electric Industries.

According to S&P Dow Jones Indices, these changes are designed to ensure each index better represents its respective market capitalization range.

This article was generated with the support of AI and reviewed by an editor. For more information see our T&C.

Here’s a summary of the most significant insider transactions disclosed on Thursday, December 4, 2025.

TOP BUYS

Standard Biotools Inc (NASDAQ:LAB) saw substantial insider buying as Casdin Partners Master Fund and related entities purchased shares worth $502,570 between December 2nd and December 4th, 2025. The fund acquired 125,000 shares on December 2nd, 75,000 shares on December 3rd, and 150,000 shares on December 4th at prices ranging from $1.4201 to $1.4468 per share. These purchases come as Standard Biotools, with a market cap of approximately $554 million, has delivered a strong 6-month price return of nearly 45%. The acquisition prices align with assessments that the stock may be slightly undervalued, with the company maintaining a healthy balance sheet featuring more cash than debt.

Alumis Inc (NASDAQ:ALMS) Director Srinivas Akkaraju made a significant investment of $2,039,900 through three separate transactions. According to SEC filings, Akkaraju purchased a total of 262,027 shares between December 2 and December 4, with prices ranging from $7.55 to $8.18 per share. Specifically, he acquired 96,000 shares on December 2, 100,000 shares on December 3, and 66,027 shares on December 4. The purchases come as Alumis has demonstrated remarkable momentum, with a 147% price return over the past six months. The company currently trades at $8.3 with a market capitalization of approximately $818 million, though technical indicators suggest the stock may be in overbought territory.

Rapid7, Inc. (NASDAQ:RPD) ten-percent owner Jana Partners Management, LP increased its stake in the company through a purchase worth approximately $652,671. The firm acquired 41,545 shares at a price of $15.71 on November 28, 2025. Following this transaction, Jana Partners Management now reports ownership of 6,760,149 shares of Rapid7.

Warner Music Group (NASDAQ:WMG) director Valentin Blavatnik purchased 35,810 shares of Class A Common Stock on December 2, 2025, in a transaction totaling $998,382. The shares were acquired at prices ranging from $27.76 to $27.91, with an average price of $27.88 per share. Following the transaction, Blavatnik directly owns 104,074 shares of Warner Music Group.

Bridger Aerospace Group Holdings, Inc. (NASDAQ:BAER) Director Jeffrey E. Kelter acquired 300,000 shares of common stock on December 3, 2025, in three separate transactions totaling $540,210. The purchases were executed at a price of $1.8007 per share, with the price range for these shares between $1.70 and $1.85.

TOP SELLS

Axsome Therapeutics (NASDAQ:AXSM) Chief Executive Officer Herriot Tabuteau sold a total of 79,973 shares between December 2 and December 4, 2025, for approximately $11.6 million. The sales were executed under a pre-approved 10b5-1 plan and involved multiple transactions with prices ranging from $144.59 to $148.18 per share. The transactions were related to the exercise of stock options expiring in May 2026. Tabuteau exercised options to acquire shares at $8.02 per share before selling them at market prices, with transactions of 49,252 shares on December 2nd, 20,163 shares on December 3rd, and 10,558 shares on December 4th. The total cost to exercise the options was $641,383.

Carvana Co (NASDAQ:CVNA) President of Special Projects Thomas Taira sold 25,000 shares of Class A Common Stock on December 3, 2025, according to an SEC Form 4 filing. The shares were sold at $400 per share, with the total transaction amounting to $10,000,000. Following the transaction, Taira directly owns 80,832 shares of Carvana. The sale was executed under a Rule 10b5-1 trading plan adopted on August 8, 2025. The transaction comes as Carvana’s stock trades near its 52-week high of $413.33, having delivered a 96% return year-to-date and 53% over the past year, with the stock currently trading at approximately its Fair Value.

Carvana Co (NYSE:CVNA) Director Michael E. Maroone sold a total of 30,928 shares of Class A Common Stock on December 3, 2025, for approximately $12,381,668. The sales included 29,576 shares at prices ranging from $400.00 to $400.99 and 1,352 shares at prices ranging from $401.02 to $401.32. On the same day, Maroone exercised options to acquire 30,928 shares at an exercise price of $15.00, for a total value of $463,920. These transactions were executed under a pre-arranged Rule 10b5-1 trading plan adopted on May 30, 2025.

Datadog (NASDAQ:DDOG) Chief Executive Officer Olivier Pomel sold a total of 48,148 shares of Class A Common Stock on December 2nd and 3rd, 2025, for approximately $7.5 million. The sales occurred in a price range of $153.8138 to $158.5985. On December 2, Pomel sold 15,225 shares at a price of $158.5985, for a total of $2,414,662. On December 3, he sold 32,923 shares in a price range of $153.8138 to $156.23, for a total of $5,090,929. The filing indicates the sales were made under a pre-arranged 10b5-1 trading plan established on September 13, 2024.

MACOM Technology Solutions Holdings, Inc. (NASDAQ:MTSI) ten percent owner Ocampo Family Trusts sold 100,000 shares of common stock on December 2nd and 3rd, 2025, for approximately $18 million. The sales were executed in two tranches, with 4,171 shares sold on December 2 at $180.00 per share, and 95,829 shares sold on December 3 at a weighted average price of $180.06. The transaction comes as MTSI shares trade near their 52-week high of $183.90, with the stock currently at $188.15 and showing significant momentum with a 9.16% return over the past week and impressive returns of 43.99% over the past six months.

Why Monitor Insider Transactions

Tracking insider buying and selling can provide valuable insights for investors. When corporate insiders purchase shares of their own companies, it often signals confidence in the company’s future prospects. Conversely, insider selling might occur for various reasons, including diversification, tax planning, or personal financial needs, and doesn’t necessarily indicate negative sentiment. By monitoring these transactions, investors can gain additional perspective on potential investment opportunities, though insider activity should be just one factor in a comprehensive investment analysis approach.

This article was generated with the support of AI and reviewed by an editor. For more information see our T&C.