Aldeyra Therapeutics, Inc. (ALDX) Ownership
ALDX ownership summary
as of October 18, 2026- Institutions
- 61.5% of shares outstanding
- Insiders
- 3.60% of shares outstanding
- Shares outstanding
- 60.3M
- Float
- 48.9M shares available to trade
- Short interest
- 5.94% 3.5M shares short
- Days to cover
- 3.70 short interest down 3.7% vs prior month
- Institutions 61.47%
- Insiders 3.60%
- Other investors 34.93%
ALDX top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Knoll Capital Management LP | 9.08% | 5.5M | $3.8M | — | June 30, 2026 |
| 2 | AQR Capital Management LLC | 6.22% | 3.8M | $2.6M | +921,683 (+32.6%) | June 30, 2026 |
| 3 | Kingdon Capital Management LLC | 4.40% | 2.7M | $1.9M | +500,000 (+23.2%) | June 30, 2026 |
| 4 | Vanguard Capital Management, LLC | 3.92% | 2.4M | $1.7M | −1,946 (−0.1%) | June 30, 2026 |
| 5 | D. E. Shaw & Co LP | 3.22% | 1.9M | $1.4M | +536,348 (+38.2%) | June 30, 2026 |
| 6 | Marshall Wace Asset Management Ltd | 2.50% | 1.5M | $1.1M | +1.4M (+1,062.0%) | June 30, 2026 |
| 7 | 683 Capital Management LLC | 2.49% | 1.5M | $1.1M | −30,000 (−2.0%) | March 31, 2026 |
| 8 | Jane Street Group LLC | 2.28% | 1.4M | $962,580 | +406,224 (+41.9%) | June 30, 2026 |
| 9 | BlackRock Inc | 2.08% | 1.3M | $880,070 | −2.5M (−66.6%) | June 30, 2026 |
| 10 | Qube Research & Technologies | 1.87% | 1.1M | $790,162 | +1.0M (+1,196.3%) | June 30, 2026 |
| 11 | Acadian Asset Management LLC | 1.76% | 1.1M | $744,655 | +205,505 (+23.9%) | June 30, 2026 |
| 12 | Ardsley Advisory Partners | 1.62% | 975K | $682,500 | +25,000 (+2.6%) | June 30, 2026 |
| 13 | Renaissance Technologies Corp | 1.46% | 882K | $617,400 | +18,813 (+2.2%) | June 30, 2026 |
| 14 | Vanguard Portfolio Management, LLC | 1.32% | 795K | $556,404 | −12,915 (−1.6%) | June 30, 2026 |
| 15 | The Goldman Sachs Group Inc | 1.20% | 725K | $507,811 | +182,298 (+33.6%) | June 30, 2026 |
| 16 | Jacobs Levy Equity Management, Inc. | 1.07% | 647K | $452,788 | −149,976 (−18.8%) | June 30, 2026 |
| 17 | Morgan Stanley - Brokerage Accounts | 1.01% | 608K | $425,825 | +89,679 (+17.3%) | June 30, 2026 |
| 18 | Geode Capital Management, LLC | 0.99% | 596K | $417,220 | −655,623 (−52.4%) | June 30, 2026 |
| 19 | Dimensional Fund Advisors, Inc. | 0.88% | 529K | $370,358 | −95,087 (−15.2%) | June 30, 2026 |
| 20 | GSA Capital Partners LLP | 0.78% | 473K | $330,795 | +225,370 (+91.2%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 12 holders added 5.5M shares and 7 cut 3.5M.
ALDX top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.96% | 1.8M | $1.2M | — | August 31, 2026 |
| 2 | Vanguard Explorer Inv | 0.55% | 332K | $232,054 | — | June 30, 2026 |
| 3 | Vanguard VIF Small Co Gr | 0.51% | 308K | $215,702 | +308,146 (0.0%) | June 30, 2026 |
| 4 | Fidelity Extended Market Index | 0.46% | 276K | $193,080 | +25,543 (+10.2%) | August 31, 2026 |
| 5 | iShares Micro-Cap ETF | 0.31% | 189K | $132,160 | −1,302 (−0.7%) | September 30, 2026 |
| 6 | Vanguard Health Care ETF | 0.28% | 168K | $117,372 | +195 (+0.1%) | September 30, 2026 |
| 7 | Invesco RAFI US 1500 Small-Mid ETF | 0.17% | 105K | $73,744 | — | September 30, 2026 |
| 8 | Fidelity Total Market Index | 0.14% | 85K | $59,809 | — | August 31, 2026 |
| 9 | Invesco NASDAQ Future Gen 200 ETF | 0.13% | 81K | $56,692 | — | September 30, 2026 |
| 10 | Fidelity Series Total Market Index | 0.12% | 73K | $50,912 | — | August 31, 2026 |
| 11 | AlphaCentric Life Sciences & Hlthcare I | 0.06% | 38K | $26,359 | +536 (+1.4%) | June 30, 2026 |
| 12 | T. Rowe Price Extended Equity Market Idx | 0.06% | 35K | $24,564 | — | September 30, 2026 |
| 13 | Vanguard Balanced Index Inv | 0.06% | 35K | $24,290 | — | August 31, 2026 |
| 14 | Fidelity ZERO Extended Market Index | 0.05% | 33K | $22,943 | +15,694 (+91.9%) | August 31, 2026 |
| 15 | Dimensional US Small Cap ETF | 0.05% | 28K | $19,691 | — | September 30, 2026 |
| 16 | Fidelity ZERO Total Market Index | 0.05% | 27K | $19,125 | — | August 31, 2026 |
| 17 | Vanguard MStar Inst Ttl StkMktIdxInstlPl | 0.04% | 21K | $14,804 | — | August 31, 2026 |
| 18 | Vanguard U.S. Eq Idx £ Acc | 0.03% | 18K | $12,381 | — | August 31, 2026 |
| 19 | JNL/DFA US Small Cap A | 0.03% | 17K | $11,894 | — | June 30, 2026 |
| 20 | Russell Inv US Small Cap Equity Y | 0.03% | 17K | $11,778 | — | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
ALDX insider transactions
latest 3| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-03-19 | Richard Douglas | Buy | $1.40 | 70,000 | $98,000 |
| 2026-03-18 | Michael Alfieri | Buy | $1.42 | 5,000 | $7,100 |
| 2025-08-11 | Stephen Machatha | Sell | $5.15 | 22,073 | $113,676 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
ALDX shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns ALDX
Institutional investors own 61.5% of Aldeyra Therapeutics's shares and insiders 3.60%. The largest holder is Knoll Capital Management LP with 9.08% of the shares (5.5M), as of June 30, 2026. Among the top 20 institutions, 12 added shares and 7 reduced their stake in the latest filings. Short interest is 5.94% of the float, or 3.70 days of average trading volume. The share count rose 802.3% since 2014.
Related: ALDX analyst forecast, ALDX key metrics. See the ALDX stock overview for the latest quote and news.
ALDX ownership FAQ
Who owns the most Aldeyra Therapeutics stock?
The largest shareholders of Aldeyra Therapeutics are Knoll Capital Management LP (9.08%), AQR Capital Management LLC (6.22%), Kingdon Capital Management LLC (4.40%), Vanguard Capital Management, LLC (3.92%), D. E. Shaw & Co LP (3.22%).
What percentage of Aldeyra Therapeutics is owned by institutions?
Institutions hold 61.5% of Aldeyra Therapeutics's shares outstanding; insiders hold 3.60%.
Which funds own Aldeyra Therapeutics?
The largest fund holders of Aldeyra Therapeutics are Vanguard MStar Total Stk Mkt Idx Invest (2.96%), Vanguard Explorer Inv (0.55%), Vanguard VIF Small Co Gr (0.51%), Fidelity Extended Market Index (0.46%), iShares Micro-Cap ETF (0.31%).
What is Aldeyra Therapeutics's short interest?
3.5M shares of Aldeyra Therapeutics were sold short, 5.94% of the float; at the average daily volume it would take 3.70 days to cover.
Are insiders buying or selling Aldeyra Therapeutics?
Of the latest 3 reported insider transactions in Aldeyra Therapeutics (since August 11, 2025), 2 were purchases and 1 were sales.
How many shares of Aldeyra Therapeutics are outstanding?
Aldeyra Therapeutics has 60.3M shares outstanding, of which 48.9M are in the public float.