Rallybio Corporation
Rallybio Corporation (RLYB) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · RLYB · as of Sep 30, 2025
Ownership Breakdown
45
Institutional Holders
▼ 3 vs Q2
$14.12M
Total Inst. Value
▲ $3.60M vs Q2
5.30M
Shares Outstanding
freeFloat 59.57%
28.29M
13F Shares Held
▼ 2.90M vs Q2
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
RLYB largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
VIKING GLOBAL INVESTORS LP pharmaceutical preparations | 4.19M | 9.31% | 9.31% | $2.09B | Nov 14, 2025 | — held |
JOHNSON & JOHNSON pharmaceutical preparations | 3.64M | 8.07% | 8.07% | $1.81B | Mar 18, 2026 | — held |
5AM VENTURE MANAGEMENT, LLC pharmaceutical preparations | 3.63M | 8.06% | 8.06% | $1.81B | Nov 14, 2025 | — held |
NEW LEAF VENTURE PARTNERS, L.L.C. pharmaceutical preparations | 3.30M | 7.33% | 7.33% | $1.65B | Nov 14, 2025 | — held |
TPG GP A, LLC pharmaceutical preparations | 3.03M | 6.72% | 6.72% | $1.51B | Nov 14, 2025 | — held |
PIVOTAL BIOVENTURE PARTNERS INVESTMENT ADVISOR LLC pharmaceutical preparations | 2.40M | 5.34% | 5.34% | $1.20B | Nov 13, 2025 | — held |
FMR LLC pharmaceutical preparations | 1.69M | 3.76% | 3.76% | $845.50M | Nov 13, 2025 | ▼ 175.9K |
ALMITAS CAPITAL LLC pharmaceutical preparations | 1.54M | 3.41% | 3.41% | $767.83M | Nov 17, 2025 | ▼ 278.8K |
VANGUARD GROUP INC pharmaceutical preparations | 999.6K | 2.22% | 2.22% | $498.81M | Nov 7, 2025 | ▲ 89.7K |
AJU IB INVESTMENT CO., LTD. pharmaceutical preparations | 754.7K | 1.67% | 1.67% | $377.34M | Nov 6, 2025 | — held |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q3 2025 vs prior quarter
Q3 2025
7
Increased
+815.4K shares6
New Positions
first time holders13
Decreased
−1.23M shares5
Sold Out
fully exitedNet shares change (top 50)
410.9K
+815.4K / −1.23M
Net new holders
-5
6 new / 5 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
RLYB insider trading · insider activity
Source: SEC Form 4
Insiders have been net buyers of shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
14
Buy transactions
0
Sell transactions
0.00
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
ADAR1 Capital Management, LLC 10 percent owner | May 19, 2026 | Purchase | 200 | $13.80 | $2.8K | 926.4K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 19, 2026 | Purchase | 10,000 | $13.98 | $139.8K | 926.2K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 18, 2026 | Purchase | 6,009 | $13.98 | $84.0K | 916.2K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 15, 2026 | Purchase | 200 | $13.95 | $2.8K | 910.1K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 15, 2026 | Purchase | 100 | $13.80 | $1.4K | 909.9K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 13, 2026 | Purchase | 75,178 | $14.00 | $1.05M | 909.8K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 13, 2026 | Purchase | 4,081 | $13.80 | $56.3K | 834.7K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 12, 2026 | Purchase | 800 | $13.83 | $11.1K | 830.6K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 11, 2026 | Purchase | 19,900 | $14.00 | $278.6K | 829.8K | Form 4 ↗ |
ADAR1 Capital Management, LLC 10 percent owner | May 11, 2026 | Purchase | 25,000 | $14.00 | $350.0K | 809.9K | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
Rallybio Corporation (RLYB) is primarily owned by institutional investors, who hold approximately 100.0% of total shares outstanding. Company insiders own approximately 40.43%, while retail and public investors account for the remaining 0.00%.
The largest institutional shareholder of Rallybio Corporation is VIKING GLOBAL INVESTORS LP, holding approximately 4.19 million shares — equal to 9.31% of outstanding shares — as of September 30, 2025.
A total of 45 institutional investors currently hold RLYB stock, with a combined institutional value of approximately $14,121,676 as of the most recent 13F filing period.
Frequently asked questions
RLYB ownershipRallybio Corporation (RLYB) is primarily owned by institutional investors, who hold approximately 100.0% of shares. The largest shareholder is VIKING GLOBAL INVESTORS LP with a 9.31% stake. Company insiders hold 40.43%. Data sourced from SEC Form 13F as of September 30, 2025.