Penbrook Management LLC — 13F Holdings & Portfolio
CIK 1381055 · latest 13F-HR filed 2026-10-16
Penbrook Management LLC manages $169.5M in 13F-reported U.S. long-equity assets across 102 reported positions as of its 2026-09-30 13F-HR filing. Its largest disclosed positions are TRGP (10.55%), AMZN (7.61%), NVO (6.97%). Quarter over quarter (versus its 2026-06-30 filing) the fund opened 6 new positions and exited 5; 35 existing positions rose in reported value and 37 fell.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
Long-equity book
Distinct positions
Filed 2026-10-16
vs 2026-06-30
Portfolio charts
Latest quarter's book, what changed, and how the portfolio has evolved across filings.
Portfolio map
Q3 26Box size = position value; colour = change in share count vs the prior quarter (green added, red trimmed, blue new). Rows split across managers or share classes are combined. Click a box for the stock.
Sector mix
% of 13F valueSectors from each company's SIC code; funds and ETFs grouped separately.
Biggest buys and sells
Q2 26 → Q3 26Estimated from the change in shares held × the quarter-end price, so price moves alone don't count as buying. New and exited positions are included.
13F assets and positions
4 quartersTotal reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.
Top positions over time
reported valueThe eight largest current positions, valued at each quarter end.
Concentration
top 10 = 50.4%Cumulative share of the portfolio held in the largest N positions.
As of the firm’s regulatory filing dated May 28, 2026.
| Name | Title / Status | Ownership | Type |
|---|---|---|---|
| ANDERSON, ROBERT, STEPHEN Control | MANAGING MEMBER since Apr 2003 | 50–75% | Individual |
| DICOSTANZO, BARBARA ANN Control | MANAGING MEMBER, CHIEF COMPLIANCE OFFICER since Apr 2003 | 25–50% | Individual |
Ownership & leadership changes · 1 filing with changes since Mar 30, 2012
From the firm’s regulatory filings, newest first. Dates are filing dates: a filing that no longer lists someone does not say when they left.
- No longer listedKAPLAN, RALPH, MOSS · MANAGING MEMBER · 10–25% · control person · listed since Apr 2003
- ChangedDICOSTANZO, BARBARA ANN · ownership 10–25% → 25–50%
- ListedANDERSON, ROBERT, STEPHEN · MANAGING MEMBER · 50–75% · control person
- ListedDICOSTANZO, BARBARA ANN · MANAGING MEMBER, CHIEF COMPLIANCE OFFICER · 10–25% · control person
- ListedKAPLAN, RALPH, MOSS · MANAGING MEMBER · 10–25% · control person
Quarter-over-quarter changes
Changes in reported position value vs the prior 13F, so price moves count too, not just shares bought or sold.
Top Adds (vs prior quarter)
- TARGA RES CORP$16.0M +867.9%
- MICROSOFT CORP$3.0M +36.2%
- SKY HARBOUR GROUP CORPORATION$1.7M +871.8%
- ALLOT LTD SHS$748.9K +30.7%
- CENOVUS ENERGY INC$585.8K +79.0%
Top Trims
- NOVO-NORDISK A S ADR-$3.3M -22.1%
- PLANET LABS PBC-$1.4M -50.8%
- ELECTROVAYA INC-$942.0K -27.5%
- EXTREME NETWORKS INC-$917.6K -33.7%
- CURIOSITYSTREAM INC CL A-$903.7K -44.4%
New Positions
- ONEOK INC NEW$964.4K
- LOCKHEED MARTIN CORP$280.1K
- EXXONMOBIL HOLDINGS CORP$208.3K
- NEWMONT CORP$205.3K
- EXAGEN INC$91.9K
Exited Positions
- DOUBLEVERIFY HLDGS INC$1.1M
- ONEOK INC$983.3K
- ANTERO MIDSTREAM CORP$225.2K
- FIRST AMERN FINL CORP$205.8K
- ONDAS INC COM NEW$82.4K
Penbrook Management LLC Holdings (2026-09-30)
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | TARGA RES CORP | TRGP | 87612G101 | $17.9M | 10.55% | 6,617 | SH |
| 2 | AMAZON COM INC | AMZN | 023135106 | $12.9M | 7.61% | 51,760 | SH |
| 3 | NOVO-NORDISK A S ADR | NVO | 670100205 | $11.8M | 6.97% | 311,500 | SH |
| 4 | MICROSOFT CORP | MSFT | 594918104 | $11.1M | 6.57% | 21,720 | SH |
| 5 | ALPHABET INC CAP STK CL A | GOOGL | 02079K305 | $8.0M | 4.70% | 23,170 | SH |
| 6 | ALPHABET INC CAP STK CL C | GOOG | 02079K107 | $7.7M | 4.51% | 22,454 | SH |
| 7 | MOODYS CORP | MCO | 615369105 | $6.2M | 3.64% | 13,600 | SH |
| 8 | CRYOPORT INC | CYRX | 229050307 | $3.5M | 2.06% | 201,085 | SH |
| 9 | ALLOT LTD SHS | ALLT | M0854Q105 | $3.2M | 1.88% | 377,395 | SH |
| 10 | SEABRIDGE GOLD INC | SA | 811927102 | $3.1M | 1.85% | 110,740 | SH |
| 11 | PHOTRONICS INC | PLAB | 719405102 | $2.7M | 1.61% | 88,855 | SH |
| 12 | MAGNITE INC | MGNI | 55955D100 | $2.7M | 1.58% | 105,690 | SH |
| 13 | MARVELL TECHNOLOGY INC | MRVL | 573874104 | $2.6M | 1.52% | 9,730 | SH |
| 14 | VIEMED HEALTHCARE INC | VMD | 92663R105 | $2.5M | 1.48% | 275,948 | SH |
| 15 | ELECTROVAYA INC | ELVA | 28617B606 | $2.5M | 1.47% | 379,606 | SH |
| 16 | THOMSON REUTERS CORP | TRI | 884903881 | $2.4M | 1.40% | 24,381 | SH |
| 17 | PROTHENA CORP PLC SHS | PRTA | G72800108 | $2.3M | 1.34% | 271,720 | SH |
| 18 | VERMILION ENERGY INC | VET | 923725105 | $2.3M | 1.33% | 197,825 | SH |
| 19 | BLACKSTONE INC | BX | 09260D107 | $2.0M | 1.20% | 18,150 | SH |
| 20 | CISCO SYS INC | CSCO | 17275R102 | $2.0M | 1.17% | 18,350 | SH |
| 21 | ALKAMI TECHNOLOGY INC | ALKT | 01644J108 | $1.9M | 1.11% | 138,010 | SH |
| 22 | SKY HARBOUR GROUP CORPORATION | SKYH | 83085C107 | $1.9M | 1.10% | 197,200 | SH |
| 23 | BAYTEX ENERGY CORP | BTE | 07317Q105 | $1.8M | 1.07% | 399,350 | SH |
| 24 | EXTREME NETWORKS INC | EXTR | 30226D106 | $1.8M | 1.06% | 84,025 | SH |
| 25 | NUVEEN N Y MUN VALUE FD | NNY | 67062M105 | $1.7M | 0.98% | 213,727 | SH |
| 26 | SONY GROUP CORP SPONSORED ADR | SONY | 835699307 | $1.6M | 0.96% | 69,500 | SH |
| 27 | AUTOMATIC DATA PROCESSING INC | ADP | 053015103 | $1.6M | 0.96% | 6,300 | SH |
| 28 | BERKSHIRE HATHAWAY INC DEL CL B NEW | BRK.B | 084670702 | $1.6M | 0.95% | 3,240 | SH |
| 29 | ENERGY TRANSFER L P COM UT LTD PTN | ET | 29273V100 | $1.5M | 0.87% | 74,293 | SH |
| 30 | BIOLIFE SOLUTIONS INC | BLFS | 09062W204 | $1.4M | 0.85% | 36,895 | SH |
| 31 | AIRBNB INC | ABNB | 009066101 | $1.4M | 0.83% | 8,750 | SH |
| 32 | VERIZON COMMUNICATIONS INC | VZ | 92343V104 | $1.4M | 0.82% | 30,424 | SH |
| 33 | AXCELIS TECHNOLOGIES INC | ACLS | 054540208 | $1.4M | 0.81% | 10,495 | SH |
| 34 | ABBVIE INC | ABBV | 00287Y109 | $1.4M | 0.81% | 5,252 | SH |
| 35 | PLANET LABS PBC | PL | 72703X106 | $1.3M | 0.79% | 81,417 | SH |
| 36 | CENOVUS ENERGY INC | CVE | 15135U109 | $1.3M | 0.78% | 42,700 | SH |
| 37 | WILLIAMS COS INC | WMB | 969457100 | $1.3M | 0.77% | 19,080 | SH |
| 38 | MESOBLAST LTD SPONS ADR | MESO | 590717401 | $1.3M | 0.75% | 87,075 | SH |
| 39 | META PLATFORMS INC CL A | META | 30303M102 | $1.2M | 0.73% | 1,700 | SH |
| 40 | STATE STREET SPDR S&P 500 ETF | SPY | 78462F103 | $1.2M | 0.72% | 1,605 | SH |
| 41 | NVIDIA CORPORATION | NVDA | 67066G104 | $1.2M | 0.71% | 5,278 | SH |
| 42 | CURIOSITYSTREAM INC CL A | CURI | 23130Q107 | $1.1M | 0.67% | 388,550 | SH |
| 43 | HESS MIDSTREAM LP CL A SHS | HESM | 428103105 | $1.1M | 0.66% | 30,005 | SH |
| 44 | DATA I O CORP | DAIO | 237690102 | $1.0M | 0.62% | 355,850 | SH |
| 45 | USA COMPRESSION PARTNERS LP | USAC | 90290N109 | $1.0M | 0.60% | 41,038 | SH |
| 46 | ONEOK INC NEW | OKE | 30609A109 | $964.4K | 0.57% | 11,310 | SH |
| 47 | SHELL PLC SPON ADS | SHEL | 780259305 | $893.5K | 0.53% | 9,400 | SH |
| 48 | PAR TECHNOLOGY CORP | PAR | 698884103 | $876.5K | 0.52% | 63,700 | SH |
| 49 | POPULAR INC | BPOP | 733174700 | $823.9K | 0.49% | 5,300 | SH |
| 50 | EMERSON ELEC CO | EMR | 291011104 | $822.0K | 0.48% | 5,300 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-09-30 | 2026-10-16 | $169.5M | 102 | 0001381055-26-000004 |
| 2026-06-30 | 2026-07-23 | $156.8M | 101 | 0001381055-26-000003 |
| 2026-03-31 | 2026-04-21 | $132.1M | 93 | 0001381055-26-000002 |
| 2025-12-31 | 2026-01-06 | $145.0M | 97 | 0001381055-26-000001 |
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