Perma-Fix Environmental Services, Inc. (PESI) Ownership
PESI ownership summary
as of October 18, 2026- Institutions
- 65.0% of shares outstanding
- Insiders
- 6.50% of shares outstanding
- Shares outstanding
- 21.2M
- Float
- 19.8M shares available to trade
- Short interest
- 16.13% 3.2M shares short
- Days to cover
- 10.25 short interest up 19.9% vs prior month
- Institutions 64.96%
- Insiders 6.50%
- Other investors 28.54%
PESI top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | BlackRock Inc | 5.90% | 1.3M | $15.4M | +82,453 (+7.0%) | June 30, 2026 |
| 2 | Mak Capital One LLC | 4.87% | 1.0M | $12.7M | +114,285 (+12.4%) | June 30, 2026 |
| 3 | Vanguard Capital Management, LLC | 3.83% | 812K | $10.0M | +52,308 (+6.9%) | June 30, 2026 |
| 4 | Prescott Group Capital Management LLC | 3.66% | 777K | $9.6M | — | June 30, 2026 |
| 5 | Diamond Hill Capital Management, LLC | 3.03% | 643K | $7.9M | +286,555 (+80.5%) | June 30, 2026 |
| 6 | Kennedy Capital Management Inc | 2.88% | 611K | $7.5M | +610,903 (0.0%) | June 30, 2026 |
| 7 | Potomac Capital Management, Inc. | 2.25% | 477K | $5.9M | +180,300 (+60.8%) | June 30, 2026 |
| 8 | Geode Capital Management, LLC | 2.15% | 455K | $5.6M | +22,455 (+5.2%) | June 30, 2026 |
| 9 | Heartland Advisors Inc | 1.89% | 400K | $4.9M | — | June 30, 2026 |
| 10 | State Street Corp | 1.65% | 350K | $4.3M | +14,197 (+4.2%) | June 30, 2026 |
| 11 | Dimensional Fund Advisors, Inc. | 0.90% | 191K | $2.4M | +27,276 (+16.7%) | June 30, 2026 |
| 12 | The Goldman Sachs Group Inc | 0.77% | 163K | $2.0M | +20,068 (+14.1%) | June 30, 2026 |
| 13 | Susquehanna International Group, LLP | 0.74% | 157K | $1.9M | +145,836 (+1,314.1%) | June 30, 2026 |
| 14 | Citadel Advisors Llc | 0.72% | 153K | $1.9M | +83,313 (+120.2%) | June 30, 2026 |
| 15 | Northern Trust Corp | 0.67% | 142K | $1.7M | +12,071 (+9.3%) | June 30, 2026 |
| 16 | Vanguard Fiduciary Trust Co | 0.58% | 123K | $1.5M | +3,787 (+3.2%) | June 30, 2026 |
| 17 | Group One Trading, LLC | 0.58% | 123K | $1.5M | −125,063 (−50.5%) | June 30, 2026 |
| 18 | Vanguard Portfolio Management, LLC | 0.57% | 121K | $1.5M | +20,949 (+20.9%) | June 30, 2026 |
| 19 | North Star Investment Management Corp | 0.57% | 121K | $1.5M | — | June 30, 2026 |
| 20 | Diametric Capital, LP | 0.54% | 115K | $1.4M | +114,714 (0.0%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 16 holders added 1.8M shares and 1 cut 125K.
PESI top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.82% | 598K | $7.4M | — | August 31, 2026 |
| 2 | iShares Russell 2000 ETF | 2.44% | 518K | $6.4M | −5,952 (−1.1%) | September 30, 2026 |
| 3 | Diamond Hill Small Cap Inv | 1.70% | 360K | $4.4M | +19,146 (+5.6%) | September 30, 2026 |
| 4 | Heartland Value Investor | 1.41% | 300K | $3.7M | — | September 30, 2026 |
| 5 | Fidelity Small Cap Index | 0.91% | 193K | $2.4M | +1,127 (+0.6%) | July 31, 2026 |
| 6 | iShares Russell 2000 Growth ETF | 0.77% | 164K | $2.0M | −207 (−0.1%) | September 30, 2026 |
| 7 | Perritt MicroCap Opportunities Investor | 0.68% | 145K | $1.8M | −8,000 (−5.2%) | December 31, 2025 |
| 8 | Vanguard Russell 2000 ETF | 0.55% | 117K | $1.4M | +15,733 (+15.5%) | September 30, 2026 |
| 9 | North Star Micro Cap I | 0.55% | 116K | $1.4M | — | September 30, 2026 |
| 10 | Fidelity Extended Market Index | 0.41% | 87K | $1.1M | +2,994 (+3.6%) | August 31, 2026 |
| 11 | Acuitas US Microcap Institutional | 0.39% | 83K | $1.0M | +32,437 (+63.7%) | June 30, 2026 |
| 12 | Range Nuclear Renaissance ETF | 0.38% | 80K | $980,319 | — | September 30, 2026 |
| 13 | iShares Micro-Cap ETF | 0.30% | 63K | $780,823 | −437 (−0.7%) | September 30, 2026 |
| 14 | Dimensional US Small Cap ETF | 0.27% | 57K | $700,833 | — | September 30, 2026 |
| 15 | Schwab Small Cap Index | 0.20% | 42K | $522,030 | — | August 31, 2026 |
| 16 | Stt Strt SPDR® Russell2000 US SmCapETF | 0.19% | 39K | $484,337 | −2,741 (−6.5%) | September 30, 2026 |
| 17 | Ancora MicroCap C | 0.17% | 37K | $454,928 | −12,043 (−24.6%) | December 31, 2025 |
| 18 | Fidelity Nasdaq Composite Index | 0.17% | 37K | $449,807 | +24,266 (+197.7%) | August 31, 2026 |
| 19 | DFA US Small Cap I | 0.16% | 34K | $418,589 | — | August 31, 2026 |
| 20 | Fidelity Total Market Index | 0.15% | 33K | $402,414 | — | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
PESI insider transactions
latest 2| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2025-09-11 | Larry Shelton | Buy | $8.58 | 1,000 | $8,580 |
| 2025-09-09 | Larry Shelton | Buy | $9.61 | 1,000 | $9,610 |
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.
PESI shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns PESI
Institutional investors own 65.0% of Perma-Fix Environmental Services's shares and insiders 6.50%. The largest holder is BlackRock Inc with 5.90% of the shares (1.3M), as of June 30, 2026. Among the top 20 institutions, 16 added shares and 1 reduced their stake in the latest filings. Short interest is 16.13% of the float, or 10.25 days of average trading volume. The share count rose 60.9% since 2014.
Related: PESI analyst forecast, PESI key metrics. See the PESI stock overview for the latest quote and news.
PESI ownership FAQ
Who owns the most Perma-Fix Environmental Services stock?
The largest shareholders of Perma-Fix Environmental Services are BlackRock Inc (5.90%), Mak Capital One LLC (4.87%), Vanguard Capital Management, LLC (3.83%), Prescott Group Capital Management LLC (3.66%), Diamond Hill Capital Management, LLC (3.03%).
What percentage of Perma-Fix Environmental Services is owned by institutions?
Institutions hold 65.0% of Perma-Fix Environmental Services's shares outstanding; insiders hold 6.50%.
Which funds own Perma-Fix Environmental Services?
The largest fund holders of Perma-Fix Environmental Services are Vanguard MStar Total Stk Mkt Idx Invest (2.82%), iShares Russell 2000 ETF (2.44%), Diamond Hill Small Cap Inv (1.70%), Heartland Value Investor (1.41%), Fidelity Small Cap Index (0.91%).
What is Perma-Fix Environmental Services's short interest?
3.2M shares of Perma-Fix Environmental Services were sold short, 16.13% of the float; at the average daily volume it would take 10.25 days to cover.
Are insiders buying or selling Perma-Fix Environmental Services?
Of the latest 2 reported insider transactions in Perma-Fix Environmental Services (since September 9, 2025), 2 were purchases and 0 were sales.
How many shares of Perma-Fix Environmental Services are outstanding?
Perma-Fix Environmental Services has 21.2M shares outstanding, of which 19.8M are in the public float.