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AMI ASSET MANAGEMENT CORP — 13F Holdings & Portfolio

CIK 1369702 · latest 13F-HR filed 2026-10-20

Backtest portfolio

AMI ASSET MANAGEMENT CORP manages $1.74B in 13F-reported U.S. long-equity assets across 100 reported positions as of its 2026-09-30 13F-HR filing. Its largest disclosed positions are AAPL (8.01%), GOOGL (5.87%), TSM (4.95%). Quarter over quarter (versus its 2026-06-30 filing) the fund opened 15 new positions and exited 14; 28 existing positions rose in reported value and 41 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
$1.74B

Long-equity book

Holdings
100

Distinct positions

Period
2026-09-30

Filed 2026-10-20

Q/Q Activity
+15 / −14 / ↑28 / ↓41

vs 2026-06-30

Portfolio charts

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

Portfolio map

Q3 26
AAPL8.0% · -4%GOOGL5.9% · -4%TSM4.9% · -3%AVGO4.7% · -4%MSFT4.7% · -4%AMZN4.5% · -4%PANW4.4% · -4%LLY3.8% · -4%PWR3.6% · -4%CRWD3.4% · +284%WST3.0% · -4%ULTA3.0% · -3%LH2.9% · -4%CHD2.8% · -4%GLW2.7% · +29%NOW2.7% · +2%BDX2.6% · -3%ECL2.4% · +59%AXON2.4% · -4%SCHW2.4% · -2%CL2.3% · -4%SPOT2.2% · +6%MA2.1% · -3%SNPS2.0% · +56%VRTX2.0% · newWM1.9% · -4%CART1.8% · -4%NFLX1.6% · -41%COST1.1% · -3%ZTS1.1% · +0%ARM1.0% · -3%CTAS0.8% · -3%MKC0.8% · -1%SPCX0.7% · -13%TJX0.7% · -12%SPY0.1% · +6%SOXX0.1% · newJNJ0.1% · +1%MRK0.1% · +1%QCOM0.1% · +1%IGV0.1% · newJPM0.1% · +1%CGON0.1% · -11%EXLS0.1% · +2%KNSA0.1% · -3%PKG0.1% · +1%FCX0.1% · +0%ARQT0.1% · +12%ELF0.1% · -2%VERA0.1% · +5%VRDN0.1% · newCSCO0.1% · +1%SRRK0.1% · -3%NUVB0.1% · -2%PEP0.1% · +1%CYTK0.1% · +4%COCO0.1% · +12%SXT0.1% · -3%PRIM0.1% · +43%GXO0.1% · -2%

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

Q2 26 → Q3 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

4 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 = 47.8%

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

Firm Profile & Key People

As of the firm’s regulatory filing dated Jul 23, 2026.

Assets Under Management
$1.93B
Discretionary
$1.93B
Employees
13
Accounts
1,221
Address
10866 WILSHIRE BLVD., STE 770
LOS ANGELES, CA 90024
Phone
(424) 320-4000
Website
Name Title / Status Ownership Type
HUMISTON, MATTHEW, TOD ControlPRESIDENT, COO
since Aug 2013
25–50%Individual
TANNER, WILLIAM, HOWARD ControlCHAIRMAN
since Aug 2013
25–50%Individual
KIM, KATHARINECHIEF COMPLIANCE OFFICER & CORPORATE SECRETARY
since Aug 2012
Less than 5%Individual
MAINSTAIN, PETERSHAREHOLDER
since Aug 2012
10–25%Individual
SESSING, CHRISTIAN, RUSSELCHIEF INVESTMENT OFFICER
since Nov 2014
5–10%Individual
ZAMFOTIS, ANDREW, STEVENPORTFOLIO MANAGER
since Nov 2021
Less than 5%Individual
Ownership & leadership changes · 6 filings with changes since Jan 31, 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.

Nov 21, 2024 filing
  • ChangedMAINSTAIN, PETER · title PARTNER → SHAREHOLDER
Nov 17, 2021 filing
  • AddedZAMFOTIS, ANDREW, STEVEN · PORTFOLIO MANAGER · Less than 5%
  • ChangedMAINSTAIN, PETER · no longer a control person
  • ChangedSESSING, CHRISTIAN, RUSSEL · ownership 10–25% → 5–10%
Jan 18, 2018 filing
  • ChangedSESSING, CHRISTIAN, RUSSEL · title SENIOR FINANCIAL ANALYST → CHIEF INVESTMENT OFFICER
Dec 2, 2016 filing
  • ChangedMAINSTAIN, PETER · ownership 25–50% → 10–25%
  • ChangedSESSING, CHRISTIAN, RUSSEL · ownership 5–10% → 10–25%
Aug 13, 2013 filing
  • ChangedHUMISTON, MATTHEW, TOD · title COO, EXECUTIVE VICE PRESIDENT → PRESIDENT, COO
  • ChangedKIM, KATHARINE · title CHIEF COMPLIANCE OFFICER / CORPORATE SECRETARY → CHIEF COMPLIANCE OFFICER & CORPORATE SECRETARY
  • ChangedTANNER, WILLIAM, HOWARD · title PRESIDENT, CEO → CHAIRMAN
Oct 17, 2012 filing
  • ChangedKIM, KATHARINE · title CHIEF COMPLIANCE OFFICER → CHIEF COMPLIANCE OFFICER / CORPORATE SECRETARY; no longer a control person
  • ChangedMAINSTAIN, PETER · title CORPORATE SECRETARY → PARTNER
  • ChangedSESSING, CHRISTIAN, RUSSEL · ownership Less than 5% → 5–10%
Jan 31, 2012 filing (earliest on record)
  • ListedHUMISTON, MATTHEW, TOD · COO, EXECUTIVE VICE PRESIDENT · 25–50% · control person
  • ListedKIM, KATHARINE · CHIEF COMPLIANCE OFFICER · Less than 5% · control person
  • ListedMAINSTAIN, PETER · CORPORATE SECRETARY · 25–50% · control person
  • ListedSESSING, CHRISTIAN, RUSSEL · SENIOR FINANCIAL ANALYST · Less than 5%
  • ListedTANNER, WILLIAM, HOWARD · PRESIDENT, CEO · 25–50% · 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.

AMI ASSET MANAGEMENT CORP 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 APPLE INC AAPL 037833100 $139.5M 8.01% 418,851 SH
2 ALPHABET INC CLASS A GOOGL 02079K305 $102.2M 5.87% 296,886 SH
3 TAIWAN SEMICONDUCTOR M F SPONS TSM 874039100 $86.1M 4.95% 188,836 SH
4 BROADCOM INC AVGO 11135F101 $82.0M 4.71% 233,379 SH
5 MICROSOFT CORP MSFT 594918104 $81.7M 4.69% 159,314 SH
6 AMAZON.COM INC AMZN 023135106 $78.8M 4.52% 316,201 SH
7 PALO ALTO NETWORKS INC PANW 697435105 $75.8M 4.36% 190,892 SH
8 ELI LILLY & CO LLY 532457108 $65.5M 3.76% 56,648 SH
9 QUANTA SVCS INC PWR 74762E102 $62.6M 3.59% 97,382 SH
10 CROWDSTRIKE HLDGS INC CLASS CL CRWD 22788C105 $58.5M 3.36% 221,128 SH
11 WEST PHARMACEUTICAL SVCS WST 955306105 $52.5M 3.01% 141,556 SH
12 ULTA BEAUTY INC ULTA 90384S303 $52.4M 3.01% 95,948 SH
13 LABCORP HLDGS INC LH 504922105 $50.5M 2.90% 163,755 SH
14 CHURCH & DWIGHT INC CHD 171340102 $48.2M 2.77% 511,288 SH
15 CORNING INC GLW 219350105 $47.4M 2.72% 308,020 SH
16 SERVICENOW INC NOW 81762P102 $47.2M 2.71% 352,058 SH
17 BECTON DICKINSON & CO BDX 075887109 $44.8M 2.57% 250,265 SH
18 ECOLAB INC ECL 278865100 $42.3M 2.43% 154,042 SH
19 AXON ENTERPRISE INC AXON 05464C101 $42.2M 2.43% 99,965 SH
20 CHARLES SCHWAB CORP NEW SCHW 808513105 $41.3M 2.37% 422,254 SH
21 COLGATE PALMOLIVE CO CL 194162103 $39.4M 2.26% 461,735 SH
22 SPOTIFY TECHNOLOGY S A F SPOT L8681T102 $39.0M 2.24% 79,985 SH
23 MASTERCARD INC CLASS CLASS A MA 57636Q104 $36.7M 2.11% 66,627 SH
24 SYNOPSYS INC SNPS 871607107 $35.2M 2.02% 80,884 SH
25 VERTEX PHARMACEUTICALS I VRTX 92532F100 $35.0M 2.01% 66,949 SH
26 WASTE MGMT INC DEL WM 94106L109 $33.8M 1.94% 165,679 SH
27 MAPLEBEAR INC CART 565394103 $30.9M 1.77% 715,598 SH
28 NETFLIX INC NFLX 64110L106 $28.4M 1.63% 408,695 SH
29 COSTCO WHSL CORP NEW COST 22160K105 $19.2M 1.10% 21,074 SH
30 ZOETIS INC CLASS CLASS A ZTS 98978V103 $18.4M 1.06% 263,803 SH
31 ARM HLDGS PLC EQUITY A F UNSPO ARM 042068205 $17.6M 1.01% 60,908 SH
32 CINTAS CORP CTAS 172908105 $13.5M 0.77% 69,032 SH
33 MCCORMICK & CO INC CLASS N MKC 579780206 $13.2M 0.76% 285,498 SH
34 SPACE EX TECH SPACEX CLASS A SPCX 84615Q103 $12.3M 0.71% 81,518 SH
35 TJX COS INC NEW TJX 872540109 $11.9M 0.68% 89,660 SH
36 STATE STREET SPDR S&P 500 ETF SPY 78462F103 $2.5M 0.14% 3,275 SH
37 ISHARES TR PHLX SEMICND ETF SOXX 464287523 $1.9M 0.11% 3,350 SH
38 JOHNSON & JOHNSON JNJ 478160104 $1.6M 0.09% 6,190 SH
39 MERCK & CO. INC. MRK 58933Y105 $1.6M 0.09% 10,800 SH
40 QUALCOMM INC QCOM 747525103 $1.5M 0.09% 8,051 SH
41 ISHARES TR EXPANDED TECH IGV 464287515 $1.4M 0.08% 13,342 SH
42 JPMORGAN CHASE & CO JPM 46625H100 $1.4M 0.08% 4,252 SH
43 CG ONCOLOGY INC CGON 156944100 $1.2M 0.07% 17,271 SH
44 EXLSERVICE HLDGS INC EXLS 302081104 $1.2M 0.07% 35,039 SH
45 KINIKSA PHARMACEUTICAL F CLASS KNSA G52694109 $1.1M 0.07% 15,341 SH
46 PACKAGING CORP OF AMER PKG 695156109 $1.1M 0.07% 4,978 SH
47 FREEPORT-MCMORAN INC FCX 35671D857 $1.1M 0.06% 16,017 SH
48 ARCUTIS BIOTHERAPEUTICS ARQT 03969K108 $1.1M 0.06% 41,505 SH
49 E L F BEAUTY INC ELF 26856L103 $1.1M 0.06% 10,566 SH
50 VERA THERAPEUTICS INC CLASS A VERA 92337R101 $1.0M 0.06% 32,028 SH
Filing History
Period Filed AUM Holdings Accession
2026-09-30 2026-10-20 $1.74B 100 0001369702-26-000014
2026-06-30 2026-07-21 $1.74B 99 0001369702-26-000010
2026-03-31 2026-04-23 $1.57B 96 0001369702-26-000008
2025-12-31 2026-01-23 $1.76B 91 0001369702-26-000003
Filer Information
Address
10866 WILSHIRE BLVD STE 770
LOS ANGELES, CA 90024
Phone
(424) 320-4003
Filing Manager
AMI ASSET MANAGEMENT CORP
LOS ANGELES, CA
Signatory
Katharine Kim
CCO