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S&CO INC — 13F Holdings & Portfolio

CIK 1082461 · latest 13F-HR filed 2026-08-06

Backtest portfolio

S&CO INC manages $1.73B in 13F-reported U.S. long-equity assets across 222 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are CAT (5.79%), BRK.B (4.74%), MSFT (4.27%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 14 new positions and exited 10; 114 existing positions rose in reported value and 56 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.

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AUM
$1.73B

Long-equity book

Holdings
222

Distinct positions

Period
2026-06-30

Filed 2026-08-06

Q/Q Activity
+14 / −10 / ↑114 / ↓56

vs 2026-03-31

Portfolio charts

Latest quarter's book, what changed, and how the portfolio has evolved across filings.

Portfolio map

Q2 26
CAT5.8% · -5%BRK.B4.7% · 0%MSFT4.3% · +4%XOM4.2% · 0%AAPL3.7% · -5%CHD3.6% · -0%ECL3.6% · -0%MRK3.2% · 0%AMZN2.7% · -0%ADP2.6% · 0%GOOG2.4% · 0%JNJ2.3% · 0%GOOGL2.0% · -0%CCJ1.8% · -4%PANW1.8% · +6%GLD1.7% · 0%APD1.6% · +0%LLY1.5% · +4%MOS1.3% · +8%PROSF1.3% · +0%TMO1.2% · -1%RPRX1.2% · -0%UNP1.1% · 0%PYPL1.1% · -2%LLYVK1.1% · -1%UNH1.1% · -0%AR1.0% · +4%ABT1.0% · -7%SIRI1.0% · -2%P0.9% · 0%XBI0.9% · 0%NVDA0.8% · 0%V0.8% · +12%FUL0.8% · -7%GEV0.8% · -4%LIN0.8% · +0%GE0.8% · -5%ALKS0.7% · 0%CSCO0.7% · -0%RHHBY0.7% · +64%FWONK0.7% · 0%MA0.7% · +4%GFL0.6% · +44%PEP0.6% · -2%AFL0.6% · 0%ADI0.5% · -4%ABNB0.5% · 0%MDT0.5% · 0%VWO0.5% · +1%JPM0.4% · -3%APO0.4% · 0%EW0.4% · 0%HD0.4% · 0%BSX0.4% · 0%MS0.4% · -1%AZN0.4% · -25%ROL0.4% · 0%CB0.4% · 0%RVMD0.4% · 0%FANG0.3% · 0%

Box 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 value

Sectors from each company's SIC code; funds and ETFs grouped separately.

Biggest buys and sells

Q1 26 → Q2 26

Estimated 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

3 quarters

Total reported 13F value (bars) and number of positions (line) each quarter. Value changes include market moves.

Top positions over time

reported value

The eight largest current positions, valued at each quarter end.

Concentration

top 10 = 38.4%

Cumulative share of the portfolio held in the largest N positions.

Firm Profile & Key People

As of the firm’s regulatory filing dated Mar 31, 2026.

Assets Under Management
$2.46B
Discretionary
$2.46B
Employees
15
Accounts
383
Address
50 CONGRESS STREET, ROOM 800
BOSTON, MA 02109
Phone
(617) 227-8660
Name Title / Status Ownership Type
JEPPSON, GEORGE, NATHANIEL ControlDIRECTOR, PRESIDENT
since Jul 2016
10–25%Individual
MCCARTHY, BRIAN, FARRELL ControlDIRECTOR, SENIOR VICE PRESIDENT, TREASURER
since Jan 2024
10–25%Individual
MEGARGEL, MATTHEW, EDWARD ControlDIRECTOR, SENIOR VICE PRESIDENT AND CLERK
since Jul 2014
10–25%Individual
QUIRK, THOMAS, VINCENT ControlDIRECTOR AND SENIOR VICE PRESIDENT
since Oct 2019
5–10%Individual
SALTONSTALL, GEORGE, WEST ControlVICE CHAIRMAN OF THE BOARD OF DIRECTORS
since Jan 2011
5–10%Individual
STILES, JOHN, BARRY ControlCHIEF COMPLIANCE OFFICER, VICE PRESIDENT
since Mar 2025
Less than 5%Individual
THOMPSON, JEFFREY, L ControlDIRECTOR, SENIOR VICE PRESIDENT
since Jan 2018
10–25%Individual
THOMPSON, NEIL, LOCKWOOD ControlDIRECTOR AND CHAIRMAN
since Jan 1996
10–25%Individual
Ownership & leadership changes · 14 filings with changes since Mar 29, 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.

Mar 31, 2025 filing
  • AddedSTILES, JOHN, BARRY · CHIEF COMPLIANCE OFFICER, VICE PRESIDENT · Less than 5% · control person
  • ChangedJEPPSON, GEORGE, NATHANIEL · title DIRECTOR, PRESIDENT, CHIEF COMPLIANCE OFFICER → DIRECTOR, PRESIDENT
  • ChangedMCCARTHY, BRIAN, FARRELL · title DIRECTOR, VICE PRESIDENT, TREASURER → DIRECTOR, SENIOR VICE PRESIDENT, TREASURER
  • ChangedQUIRK, THOMAS, VINCENT · ownership 10–25% → 5–10%
  • ChangedTHOMPSON, JEFFREY, L · title DIRECTOR, VICE PRESIDENT → DIRECTOR, SENIOR VICE PRESIDENT
Mar 29, 2024 filing
  • No longer listedMITCHELL, JERROLD · DIRECTOR AND SENIOR VICE PRESIDENT · 5–10% · control person · listed since Jan 2009
  • Listed againMCCARTHY, BRIAN, FARRELL · DIRECTOR, VICE PRESIDENT, TREASURER · 10–25% · control person
  • ChangedJEPPSON, GEORGE, NATHANIEL · title DIRECTOR, PRESIDENT, TREASURER, CHIEF COMPLIANCE OFFICER → DIRECTOR, PRESIDENT, CHIEF COMPLIANCE OFFICER
  • ChangedTHOMPSON, JEFFREY, L · title VICE PRESIDENT → DIRECTOR, VICE PRESIDENT
  • ChangedTHOMPSON, NEIL, LOCKWOOD · ownership 25–50% → 10–25%
Mar 31, 2023 filing
  • No longer listedLEWIS, GEORGE · DIRECTOR · 5–10% · control person · listed since Apr 1988
Mar 31, 2022 filing
  • ChangedLEWIS, GEORGE · ownership 10–25% → 5–10%
  • ChangedTHOMPSON, JEFFREY, L · ownership 5–10% → 10–25%
Mar 30, 2021 filing
  • ChangedMITCHELL, JERROLD · ownership 10–25% → 5–10%
Mar 27, 2020 filing
  • AddedQUIRK, THOMAS, VINCENT · DIRECTOR AND SENIOR VICE PRESIDENT · 10–25% · control person
  • ChangedSALTONSTALL, GEORGE, WEST · title DIRECTOR → VICE CHAIRMAN OF THE BOARD OF DIRECTORS
Mar 29, 2019 filing
  • No longer listedMCCARTHY, BRIAN, FARRELL · VICE PRESIDENT · Less than 5% · control person · listed since Jan 2018
  • No longer listedWEBB, (III), ALEXANDER · DIRECTOR · 10–25% · control person · listed since Oct 2004
  • ChangedJEPPSON, GEORGE, NATHANIEL · title DIRECTOR, SENIOR VICE PRESIDENT, TREASURER, CHIEF COMPLIANCE OFFICER → DIRECTOR, PRESIDENT, TREASURER, CHIEF COMPLIANCE OFFICER; ownership 5–10% → 10–25%
  • ChangedMEGARGEL, MATTHEW, EDWARD · ownership 5–10% → 10–25%
  • ChangedTHOMPSON, JEFFREY, L · ownership Less than 5% → 5–10%
  • ChangedTHOMPSON, NEIL, LOCKWOOD · title DIRECTOR, CHAIRMAN, PRESIDENT → DIRECTOR AND CHAIRMAN
Apr 18, 2018 filing
  • No longer listedMCCARTHY, BRIAN, F · VICE PRESIDENT · Less than 5% · control person · listed since Jan 2018
  • AddedMCCARTHY, BRIAN, FARRELL · VICE PRESIDENT · Less than 5% · control person
Jan 11, 2018 filing
  • AddedMCCARTHY, BRIAN, F · VICE PRESIDENT · Less than 5% · control person
  • AddedTHOMPSON, JEFFREY, L · VICE PRESIDENT · Less than 5% · control person
  • ChangedJEPPSON, GEORGE, NATHANIEL · title DIRECTOR → DIRECTOR, SENIOR VICE PRESIDENT, TREASURER, CHIEF COMPLIANCE OFFICER
  • ChangedMEGARGEL, MATTHEW, EDWARD · title DIRECTOR AND ASSISTANT CLERK → DIRECTOR, SENIOR VICE PRESIDENT AND CLERK
  • ChangedMITCHELL, JERROLD · title DIRECTOR → DIRECTOR AND SENIOR VICE PRESIDENT
  • ChangedTHOMPSON, NEIL, LOCKWOOD · title DIRECTOR, CHAIRMAN → DIRECTOR, CHAIRMAN, PRESIDENT
  • ChangedWEBB, (III), ALEXANDER · title DIRECTOR, CHIEF COMPLIANCE OFFICER, TREASURER AND CLERK, & PRESIDENT → DIRECTOR
Mar 30, 2017 filing
  • AddedJEPPSON, GEORGE, NATHANIEL · DIRECTOR · 5–10% · control person
  • ChangedLEWIS, GEORGE · ownership 25–50% → 10–25%
Older changes (5 more filings)
Mar 30, 2016 filing
  • ChangedTHOMPSON, NEIL, LOCKWOOD · title DIRECTOR, CHAIRMAN & PRESIDENT → DIRECTOR, CHAIRMAN
  • ChangedWEBB, (III), ALEXANDER · title DIRECTOR, CHIEF COMPLIANCE OFFICER, TREASURER AND CLERK → DIRECTOR, CHIEF COMPLIANCE OFFICER, TREASURER AND CLERK, & PRESIDENT
Jul 2, 2014 filing
  • AddedMEGARGEL, MATTHEW, EDWARD · DIRECTOR AND ASSISTANT CLERK · 5–10% · control person
Jun 16, 2014 filing
  • No longer listedWILLIS, DUDLEY, HALL · TREASURER, CLERK, DIRECTOR · 10–25% · control person · listed since Apr 1988
  • ChangedLEWIS, GEORGE · ownership 10–25% → 25–50%
  • ChangedSALTONSTALL, GEORGE, WEST · ownership Less than 5% → 5–10%
  • ChangedTHOMPSON, NEIL, LOCKWOOD · ownership 10–25% → 25–50%
  • ChangedWEBB, (III), ALEXANDER · title DIRECTOR, CHIEF COMPLIANCE OFFICER → DIRECTOR, CHIEF COMPLIANCE OFFICER, TREASURER AND CLERK
Mar 31, 2014 filing
  • ChangedTHOMPSON, NEIL, LOCKWOOD · title DIRECTOR & PRESIDENT → DIRECTOR, CHAIRMAN & PRESIDENT
Mar 29, 2012 filing (earliest on record)
  • ListedLEWIS, GEORGE · DIRECTOR · 10–25% · control person
  • ListedMITCHELL, JERROLD · DIRECTOR · 10–25% · control person
  • ListedSALTONSTALL, GEORGE, WEST · DIRECTOR · Less than 5% · control person
  • ListedTHOMPSON, NEIL, LOCKWOOD · DIRECTOR & PRESIDENT · 10–25% · control person
  • ListedWEBB, (III), ALEXANDER · DIRECTOR, CHIEF COMPLIANCE OFFICER · 10–25% · control person
  • ListedWILLIS, DUDLEY, HALL · TREASURER, CLERK, DIRECTOR · 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.

S&CO INC Holdings (2026-06-30)

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 CATERPILLAR INC. CAT 149123101 $100.2M 5.79% 94,076 SH
2 BERKSHIRE HATHAWAY INC CL B BRK.B 084670702 $82.1M 4.74% 164,075 SH
3 MICROSOFT CORP MSFT 594918104 $74.0M 4.27% 198,340 SH
4 EXXONMOBIL HOLDINGS CORP XOM 30233Q108 $71.9M 4.15% 526,003 SH
5 APPLE INC AAPL 037833100 $63.9M 3.69% 220,707 SH
6 CHURCH & DWIGHT CO INC CHD 171340102 $62.9M 3.64% 649,655 SH
7 ECOLAB INC ECL 278865100 $62.9M 3.64% 225,862 SH
8 MERCK & CO INC MRK 58933Y105 $54.7M 3.16% 425,528 SH
9 AMAZON.COM INC AMZN 023135106 $46.9M 2.71% 196,975 SH
10 AUTOMATIC DATA PROCESSING INC ADP 053015103 $45.2M 2.61% 201,978 SH
11 ALPHABET INC CLASS C GOOG 02079K107 $41.7M 2.41% 118,113 SH
12 JOHNSON & JOHNSON JNJ 478160104 $39.9M 2.30% 157,098 SH
13 ALPHABET INC CAP STK CL A GOOGL 02079K305 $33.9M 1.96% 94,857 SH
14 CAMECO CORP CCJ 13321L108 $31.9M 1.85% 313,626 SH
15 PALO ALTO NETWORKS INC PANW 697435105 $31.3M 1.81% 91,852 SH
16 SPDR GOLD TRUST GLD 78463V107 $29.7M 1.71% 80,565 SH
17 AIR PRODUCTS & CHEMICALS INC C APD 009158106 $27.7M 1.60% 94,594 SH
18 ELI LILLY & CO COM LLY 532457108 $26.7M 1.55% 22,300 SH
19 MOSAIC COMPANY MOS 61945C103 $22.1M 1.27% 1,040,723 SH
20 PROSUS NV -SPON ADR PROSF 74365P108 $21.7M 1.25% 2,499,611 SH
21 THERMO FISHER SCIENTIFIC INC C TMO 883556102 $20.7M 1.20% 41,387 SH
22 ROYALTY PHARMA PLC CL A RPRX G7709Q104 $20.1M 1.16% 358,302 SH
23 UNION PACIFIC CORP UNP 907818108 $18.9M 1.09% 69,353 SH
24 PAYPAL HOLDINGS INC PYPL 70450Y103 $18.8M 1.09% 436,017 SH
25 LIBERTY MEDIA CORP-LIBERTY LIV LLYVK 530909308 $18.5M 1.07% 174,783 SH
26 UNITEDHEALTH GROUP INC COM UNH 91324P102 $18.3M 1.06% 43,984 SH
27 ANTERO RESOURCES CORP AR 03674X106 $17.7M 1.02% 504,602 SH
28 ABBOTT LABS ABT 002824100 $16.9M 0.98% 186,521 SH
29 SIRIUS XM HOLDINGS INC SIRI 829933100 $16.8M 0.97% 569,206 SH
30 EVERPURE, INC. CLASS A P 74624M102 $15.0M 0.87% 190,420 SH
31 SPDR S&P BIOTECH ETF XBI 78464A870 $14.9M 0.86% 94,310 SH
32 NVIDIA CORP COM NVDA 67066G104 $14.4M 0.83% 72,156 SH
33 VISA INC. CL A V 92826C839 $14.4M 0.83% 41,890 SH
34 H.B. FULLER CO. FUL 359694106 $14.1M 0.81% 241,781 SH
35 GE VERNOVA INC GEV 36828A101 $13.8M 0.80% 11,732 SH
36 LINDE PLC LIN G54950103 $13.6M 0.78% 26,139 SH
37 GE AEROSPACE COM (NEW) GE 369604301 $13.3M 0.77% 35,671 SH
38 ALKERMES PLC ALKS G01767105 $12.8M 0.74% 244,760 SH
39 CISCO SYSTEMS INC COM CSCO 17275R102 $12.6M 0.73% 107,126 SH
40 ROCHE HOLDING LTD SPONSORED AD RHHBY 771195104 $11.9M 0.69% 230,310 SH
41 LIBERTY FORMULA ONE SER C FWONK 531229755 $11.7M 0.67% 122,528 SH
42 MASTERCARD INC - A MA 57636Q104 $11.5M 0.66% 22,358 SH
43 GFL ENVIRONMENTAL GFL 36168Q104 $10.8M 0.62% 293,524 SH
44 PEPSICO INC PEP 713448108 $10.2M 0.59% 75,677 SH
45 AFLAC INC COM AFL 001055102 $9.8M 0.57% 83,570 SH
46 ANALOG DEVICES INC COM ADI 032654105 $9.4M 0.55% 23,789 SH
47 AIRBNB INC A ABNB 009066101 $8.9M 0.52% 62,355 SH
48 MEDTRONIC PLC MDT G5960L103 $8.5M 0.49% 108,128 SH
49 VANGUARD FTSE EMERGING MARKET VWO 922042858 $7.9M 0.46% 132,538 SH
50 JP MORGAN CHASE & CO JPM 46625H100 $7.6M 0.44% 23,285 SH
Filing History
Period Filed AUM Holdings Accession
2026-06-30 2026-08-06 $1.73B 222 0001082461-26-000003
2026-03-31 2026-05-07 $1.61B 218 0001082461-26-000002
2025-12-31 2026-02-05 $1.61B 218 0001082461-26-000001
Filer Information
Address
50 CONGRESS STREET ROOM 800
BOSTON, MA 02109
Phone
(617) 227-8660
Filing Manager
S&CO INC
BOSTON, MA
Signatory
Jason Ries
Operations