Inhibrx Biosciences (NASDAQ:INBX) Stock Price Up 9.9% Following Insider Buying Activity

Posted by Brian Himes on Sep 9th, 2026

Inhibrx Biosciences, Inc. (NASDAQ:INBX – Get Free Report)’s stock price traded up 9.9% during mid-day trading on Wednesday after an insider bought additional shares in the company. The company traded as high as $126.48 and last traded at $125.6080. Approximately 98,845 shares changed hands during trading, a decline of 69% from the average session volume of 318,316 shares. The stock had previously closed at $114.34.

Specifically, Director Jon Kayyem purchased 5,000 shares of Inhibrx Biosciences stock in a transaction on Tuesday, September 8th. The shares were bought at an average price of $113.52 per share, with a total value of $567,600.00. Following the transaction, the director directly owned 424,360 shares of the company’s stock, valued at approximately $48,173,347.20. This trade represents a 1.19% increase in their ownership of the stock. The transaction was disclosed in a document filed with the Securities & Exchange Commission, which can be accessed through the SEC website. Also, CEO Mark Lappe acquired 25,000 shares of the stock in a transaction dated Tuesday, September 8th. The shares were bought at an average cost of $105.82 per share, with a total value of $2,645,500.00. Following the completion of the transaction, the chief executive officer owned 730,548 shares of the company’s stock, valued at approximately $77,306,589.36. This represents a 3.54% increase in their position. The SEC filing for this purchase provides additional information. In other news, Director Douglas Forsyth bought 2,500 shares of Inhibrx Biosciences stock in a transaction that occurred on Tuesday, September 8th. The shares were purchased at an average price of $114.65 per share, with a total value of $286,625.00. Following the completion of the acquisition, the director directly owned 227,064 shares in the company, valued at $26,032,887.60. The trade was a 1.11% increase in their ownership of the stock. The acquisition was disclosed in a legal filing with the Securities & Exchange Commission, which can be accessed through this link.

Wall Street Analysts Forecast Growth

INBX has been the subject of several analyst reports. Weiss Ratings reiterated a “sell (d-)” rating on shares of Inhibrx Biosciences in a report on Tuesday, June 16th. HC Wainwright started coverage on shares of Inhibrx Biosciences in a research report on Monday, August 24th. They set a “buy” rating and a $245.00 price objective for the company. Citigroup reiterated a “market perform” rating on shares of Inhibrx Biosciences in a research note on Thursday, August 27th. Finally, Wall Street Zen lowered Inhibrx Biosciences from a “hold” rating to a “strong sell” rating in a report on Monday, August 17th. One analyst has rated the stock with a Strong Buy rating, two have issued a Buy rating, two have assigned a Hold rating and one has issued a Sell rating to the stock. According to MarketBeat, Inhibrx Biosciences has a consensus rating of “Moderate Buy” and an average price target of $197.50.

Read Our Latest Stock Report on INBX

Key Headlines Impacting Inhibrx Biosciences

Here are the key news stories impacting Inhibrx Biosciences this week:

Positive Sentiment: Strong head-and-neck cancer data: INBRX-106 combined with Merck’s Keytruda produced a 48.3% confirmed overall response rate, compared with 26.5% for Keytruda alone. Six-month progression-free survival was 72.4% versus 42.8%, while interim median progression-free survival reached 9.6 months. Inhibrx Phase 2 HNSCC study results
Positive Sentiment: Especially compelling HPV-positive results: The combination delivered an 80.0% response rate versus 33.3% for Keytruda alone, a 30.0% complete-response rate versus zero for monotherapy, and a substantial improvement in six-month progression-free survival. Reuters report on Inhibrx cancer study
Positive Sentiment: Management insider buying: CEO Mark Lappe bought 25,000 shares for approximately $2.65 million. Directors Jon Kayyem and Douglas Forsyth also purchased 5,000 and 2,500 shares, respectively, signaling management confidence in INBX’s outlook. Inhibrx CEO insider purchase
Neutral Sentiment: Additional development planned: Inhibrx intends to add approximately 50 HPV-positive patients to the Phase 2 study and may pursue an accelerated-approval pathway. Ozekibart also remains a longer-term catalyst, with an FDA biologics decision expected by April 2027.
Negative Sentiment: Why the response remains restrained: The HNSCC findings are from a mid-stage trial and require confirmation, expanded enrollment and regulatory review. Investors may also be taking profits after INBX’s earlier gains, while the company remains loss-making and reported quarterly EPS below consensus. The stock’s high volatility further amplifies the reaction to changing expectations.

Inhibrx Biosciences Price Performance

The company has a debt-to-equity ratio of 12.58, a quick ratio of 5.07 and a current ratio of 5.07. The stock’s 50-day moving average is $98.17 and its 200 day moving average is $92.74. The stock has a market capitalization of $1.82 billion, a PE ratio of -14.15 and a beta of 3.66.

Inhibrx Biosciences (NASDAQ:INBX – Get Free Report) last announced its quarterly earnings results on Thursday, August 13th. The company reported ($2.34) EPS for the quarter, missing the consensus estimate of ($2.28) by ($0.06). As a group, equities analysts expect that Inhibrx Biosciences, Inc. will post -9.91 earnings per share for the current year.

Institutional Trading of Inhibrx Biosciences

Institutional investors and hedge funds have recently made changes to their positions in the company. Integrated Wealth Concepts LLC acquired a new stake in shares of Inhibrx Biosciences in the 2nd quarter valued at about $31,000. Persistent Asset Partners Ltd acquired a new position in Inhibrx Biosciences during the fourth quarter worth approximately $27,000. Quantbot Technologies LP purchased a new stake in Inhibrx Biosciences in the second quarter valued at approximately $68,000. BNP Paribas Financial Markets lifted its stake in Inhibrx Biosciences by 71.9% in the third quarter. BNP Paribas Financial Markets now owns 1,886 shares of the company’s stock valued at $64,000 after buying an additional 789 shares during the last quarter. Finally, Daiwa Securities Group Inc. acquired a new stake in shares of Inhibrx Biosciences in the fourth quarter valued at approximately $66,000. 82.46% of the stock is owned by hedge funds and other institutional investors.

About Inhibrx Biosciences

(Get Free Report)

Inhibrx, Inc, headquartered in La Jolla, California, is a clinical-stage biotechnology company focused on the discovery and development of next-generation protein therapeutics. The company’s proprietary protein engineering platform enables the design and production of multispecific and multivalent biologics with tailored binding characteristics and favorable pharmacokinetic properties. By leveraging high-throughput screening and structure-based design, Inhibrx aims to create molecules that address challenging targets in oncology, regenerative medicine and other areas of unmet medical need.

The company’s lead candidate, INBRX-109, is a tetravalent agonist of the receptor tyrosine kinase ROR2 designed to stimulate tissue repair and regeneration.