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Axcelis Technologies (ACLS) Institutional Ownership & Insider Trading History

Top ACLS institutional shareholders, filing changes, and Form 4 insider activity with filters for buys, sales, option exercises, gifts, and tax withholding.

Section freshness

Prices as of Sep 29, 9:50 AM EDT · Fundamentals checked Sep 29, 9:39 AM EDT · Statements Jun 30, 2026

Ownership read

ACLS insider transaction activity: Net selling.

Blackrock Inc. is the largest institutional holder. 23 sales and 0 purchases appear in the recent Form 4 filings. Use the filters below to separate open-market activity from option exercises, gifts, awards, and tax withholding.

Review insider tradesView institutions

Insider flow

ACLS

Purchases0
Sales47.05K

Directional bars ignore awards, gifts, conversions, and tax withholding rows.

Top holder

5.03M

Blackrock Inc.

Insider transaction activity

Net selling

$6.52M sold / $0.0000 bought

Observations shown

63

10 holder / 53 insider

Holder rows
10
Yahoo Finance · Filing dates shown per row
Increased / initiated
5
5 decreased · provider-reported changes
Insider rows
53
Yahoo Finance · Filing dates shown per row

Ownership concentration and transaction activity

Top 10 reported holders
60.44% outstanding
Changes with share-count history
Prior-position data unavailable
New / exited positions
0 / 0 explicitly reported
Largest increase with share-count history
Prior share counts unavailable

Reported-holder cohort only; absence from a limited provider list does not establish an exit. Changes are provider-reported and are only comparable quarter over quarter when the position periods match.

Net shares sold: 47,054

Sale-code S shares minus purchase-code P shares in this sample. Includes disclosed plans and unknown plan status; excludes grants, gifts, exercises and withholding. This is activity, not sentiment.

  • Purchase / sale; plan unknown: 23
  • Grant: 30

Top 10 institutional holders

Axcelis Technologies (ACLS) institutional ownership

Ranked by reported share count, with position changes and separate position and filing dates where ownership data supplies them.

Axcelis Technologies (ACLS) institutional ownership
#Institution% heldSharesChange %Position / filing date
1
Blackrock Inc.
16.3%5.03M+1.88%Position as of Jun 30, 2026Filing date unknown
2
FMR, LLC
13.4%4.13M+69.71%Position as of Jun 30, 2026Filing date unknown
3
Vanguard Portfolio Management LLC
8.03%2.48M-0.38%Position as of Jun 30, 2026Filing date unknown
4
Vanguard Capital Management LLC
4.49%1.39M+0.27%Position as of Jun 30, 2026Filing date unknown
5
State Street Corporation
3.99%1.23M+3.54%Position as of Jun 30, 2026Filing date unknown
6
Victory Capital Management Inc.
3.67%1.13M-11.34%Position as of Jun 30, 2026Filing date unknown
7
Reinhart Partners, LLC
3.01%928.66K-43.98%Position as of Jun 30, 2026Filing date unknown
8
Geode Capital Management, LLC
2.70%833.61K+2.75%Position as of Jun 30, 2026Filing date unknown
9
BNP Paribas Asset Management Holding S.A.
2.60%803.15K-20.17%Position as of Jun 30, 2026Filing date unknown
10
Dimensional Fund Advisors LP
2.30%709.27K-15.97%Position as of Jun 30, 2026Filing date unknown
Showing 10 of 10 matching institutional rows.

Recent insider transactions

Axcelis Technologies (ACLS) Form 4 filings

Action codes are translated so open-market buys and sales are separate from awards, gifts, conversions, and tax withholding.

Axcelis Technologies (ACLS) Form 4 insider transactions
#Insider% companyActionSharesTransaction date
1
SAYINER NECIP
Director
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

1.59KJun 3, 2026
2
MAHONEY ROBERT JOHN
Officer
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

1.16KJun 2, 2026
3
SUTTON TODD
Officer
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

2.00KMay 27, 2026
4
EVANS EILEEN
General Counsel
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

926May 22, 2026
5
ST DENNIS THOMAS
Director
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

900May 22, 2026
6
BLUMENSTOCK GERALD M
Officer
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

1.16KMay 21, 2026
7
TATNALL CHRISTOPHER
Officer
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

1.17KMay 20, 2026
8
QUIRK JEANNE
Director
<0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

1.79KMay 19, 2026
9
GRAVES GREGORY B
Director
0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

3.23KMay 19, 2026
10
KURTZWEIL JOHN THOMAS
Director
0.01%SaleOpen-market or direct sale reported on Form 4.
Transaction context
Classification:
Purchase / sale; plan unknown
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

3.50KMay 19, 2026
11
REDINBO GREGORY F
Officer
0.02%Stock Award(Grant)Provider-supplied Form 4 action code. Review the original filing before making a trading judgment.
Transaction context
Classification:
Grant
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

6.23KMay 15, 2026
12
EVANS EILEEN
General Counsel
0.03%Stock Award(Grant)Provider-supplied Form 4 action code. Review the original filing before making a trading judgment.
Transaction context
Classification:
Grant
10b5-1:
Unknown; not supplied by provider
Holdings after:
Not reported
Position sold:
Not calculable
Filed:
Not reported

Position sold = shares sold ÷ (shares sold + holdings after). Separate accounts or security classes may not represent total beneficial ownership.

7.79KMay 15, 2026
Showing 12 of 53 matching Form 4 rows. Percent of company uses current shares outstanding.

Frequently asked

Common questions.

Who are the largest ACLS shareholders?

Blackrock Inc. is the largest reported institutional holder of ACLS, with 5.03 million shares, or about 16.29% of shares outstanding.

What does the institutional filing activity show for ACLS?

Axcelis Technologies has 10 institutional rows on file: 5 increased or initiated positions and 5 reduced them.

What insider transactions are available for ACLS?

TECHi shows 53 dated ACLS insider transactions through Jun 3, 2026, with transaction types kept separate so administrative actions are not presented as open-market trades.

Are ACLS insiders buying or selling?

The displayed ACLS activity reads Net selling: 23 sales and 0 purchases. Other transaction types remain separate.

Who is the most active reported ACLS insider?

LOW RUSSELL J has the largest absolute share movement in the displayed ACLS filing rows, totaling 111,608 shares. The action labels provide the transaction context.

All data sources

Search the dated figures used for this view. Each entry identifies its units, reporting period and calculation status.

How to use this page

Use this to check who owns the float and whether insiders are active.

Best for Institutional concentration, insider transaction pattern, and float context.

Weak when Filings are delayed or transactions are administrative rather than economic.

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