Insider Buying: Rallybio (NASDAQ:RLYB) Major Shareholder Purchases 10,200 Shares of Stock

Posted by Stanley Muller on May 20th, 2026

Rallybio Corporation (NASDAQ:RLYB – Get Free Report) major shareholder Adar1 Capital Management, Llc acquired 10,200 shares of Rallybio stock in a transaction dated Tuesday, May 19th. The shares were purchased at an average cost of $13.98 per share, with a total value of $142,596.00. Following the completion of the transaction, the insider directly owned 926,352 shares of the company’s stock, valued at $12,950,400.96. This trade represents a 1.11% increase in their ownership of the stock. The acquisition was disclosed in a legal filing with the SEC, which is available at this hyperlink. Major shareholders that own at least 10% of a company’s shares are required to disclose their sales and purchases with the SEC.

Adar1 Capital Management, Llc also recently made the following trade(s):

On Monday, May 18th, Adar1 Capital Management, Llc acquired 6,009 shares of Rallybio stock. The shares were purchased at an average cost of $13.98 per share, with a total value of $84,005.82.
On Friday, May 15th, Adar1 Capital Management, Llc acquired 300 shares of Rallybio stock. The shares were purchased at an average cost of $13.90 per share, with a total value of $4,170.00.
On Wednesday, May 13th, Adar1 Capital Management, Llc acquired 79,259 shares of Rallybio stock. The shares were purchased at an average cost of $13.99 per share, with a total value of $1,108,833.41.
On Tuesday, May 12th, Adar1 Capital Management, Llc bought 800 shares of Rallybio stock. The shares were bought at an average price of $13.83 per share, for a total transaction of $11,064.00.
On Monday, May 11th, Adar1 Capital Management, Llc bought 50,000 shares of Rallybio stock. The shares were bought at an average price of $14.00 per share, for a total transaction of $700,000.00.
On Tuesday, May 5th, Adar1 Capital Management, Llc bought 35,101 shares of Rallybio stock. The shares were bought at an average price of $14.00 per share, for a total transaction of $491,414.00.
On Monday, May 4th, Adar1 Capital Management, Llc bought 120,804 shares of Rallybio stock. The shares were bought at an average price of $13.97 per share, for a total transaction of $1,687,631.88.

Rallybio Stock Performance

RLYB traded up $0.39 on Wednesday, hitting $14.58. 43,720 shares of the company were exchanged, compared to its average volume of 642,666. Rallybio Corporation has a 12 month low of $2.16 and a 12 month high of $15.31. The company has a market cap of $77.27 million, a PE ratio of -3.20 and a beta of -1.10. The stock’s fifty day moving average is $10.05 and its 200-day moving average is $7.25.

Rallybio (NASDAQ:RLYB – Get Free Report) last released its earnings results on Wednesday, May 13th. The company reported ($1.46) earnings per share (EPS) for the quarter, missing the consensus estimate of ($1.20) by ($0.26). Rallybio had a negative return on equity of 55.79% and a negative net margin of 911.07%.The company had revenue of $0.21 million for the quarter, compared to the consensus estimate of $0.21 million.

Wall Street Analyst Weigh In

Several analysts recently issued reports on RLYB shares. Wall Street Zen upgraded Rallybio to a “hold” rating in a report on Saturday, March 28th. Weiss Ratings restated a “sell (d-)” rating on shares of Rallybio in a research note on Friday, May 8th. One investment analyst has rated the stock with a Sell rating, According to MarketBeat.com, the stock currently has an average rating of “Sell”.

Read Our Latest Report on Rallybio

Institutional Trading of Rallybio

Several institutional investors and hedge funds have recently bought and sold shares of RLYB. Citadel Advisors LLC raised its stake in Rallybio by 576.1% in the third quarter. Citadel Advisors LLC now owns 438,705 shares of the company’s stock valued at $219,000 after buying an additional 373,821 shares during the period. Renaissance Technologies LLC raised its stake in Rallybio by 16.9% in the fourth quarter. Renaissance Technologies LLC now owns 835,692 shares of the company’s stock valued at $573,000 after buying an additional 120,892 shares during the period. Susquehanna International Group LLP raised its stake in Rallybio by 485.9% in the third quarter. Susquehanna International Group LLP now owns 136,294 shares of the company’s stock valued at $68,000 after buying an additional 113,031 shares during the period. XTX Topco Ltd raised its stake in Rallybio by 64.6% in the fourth quarter. XTX Topco Ltd now owns 97,313 shares of the company’s stock valued at $67,000 after buying an additional 38,205 shares during the period. Finally, Geode Capital Management LLC raised its stake in Rallybio by 1.2% in the fourth quarter. Geode Capital Management LLC now owns 248,005 shares of the company’s stock valued at $170,000 after buying an additional 2,996 shares during the period. Institutional investors own 90.34% of the company’s stock.

Rallybio Company Profile

(Get Free Report)

Rallybio Therapeutics, Inc (NASDAQ: RLYB) is a clinical‐stage biotechnology company focused on developing and commercializing therapies for people living with rare genetic diseases. The company’s scientific approach leverages diverse modalities—including monoclonal antibodies, small molecules and enzyme replacement—to address high‐unmet‐need conditions in areas such as immunodeficiency, metabolic disorders and dermatologic diseases. Rallybio’s pipeline is designed to advance through registrational clinical trials with the goal of delivering first‐in‐class or best‐in‐class therapies to patients who currently have limited or no approved treatment options.

Among Rallybio’s lead programs is RBX‐100, an investigational therapy for congenital athymia, a rare pediatric immunodeficiency.