Beneficial Ownership Report · SCHEDULE 13D/A

GrafTech International Ltd.

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Beneficial Ownership Report

Filed Sep 18, 2026Accepted Sep 18, 2026, 4:45 PM EDTFiling CIK 931148Accession 0001944761-26-000004

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Structured filing — SCHEDULE 13D/A

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Amendment · This filing reports the amendment as submitted.

Subject company

Company: GRAFTECH INTERNATIONAL LTD
Company CIK: 0000931148
Street: 982 KEYNOTE CIRCLE
City: BROOKLYN HEIGHTS
State / country code: OH
Postal code: 44131

Statement details

Amendment number: 3
Security class: Common Stock
Event date: 09/16/2026
Previously filed indication: false

Authorized notification person 1

Name: Nilesh Undavia
Phone: (617) 763-8191
Street: 474 NE 3rd Street
City: Boca Raton
State / country code: FL
Postal code: 33432

Reporting person 1

Name: Undavia Nilesh
Reporting person CIK: 0001944761
No reporting person CIK indication: N
Citizenship / organization: X1
Reporting person type: IN
Group designation: a
Source of funds code: PF
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 1,282,474.00
Shared voting power: 929,030.00
Sole dispositive power: 1,282,474.00
Shared dispositive power: 929,030.00
Aggregate excludes certain shares: N

Reporting person 2

Name: Liliana Undavia
No reporting person CIK indication: Y
Citizenship / organization: X1
Reporting person type: IN
Group designation: a
Source of funds code: PF
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 281,000.00
Shared voting power: 1,930,504.00
Sole dispositive power: 281,000.00
Shared dispositive power: 1,930,504.00
Aggregate excludes certain shares: N

Reporting person 3

Name: Kanta Undavia
No reporting person CIK indication: Y
Citizenship / organization: K7
Reporting person type: IN
Group designation: a
Source of funds code: PF
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 0.00
Shared voting power: 2,211,504.00
Sole dispositive power: 0.00
Shared dispositive power: 2,211,504.00
Aggregate excludes certain shares: N

Reporting person 4

Name: The Nilesh P Undavia 2018 Trust u/a Dated 10/25/2018
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 568,030.00
Shared voting power: 1,643,474.00
Sole dispositive power: 568,030.00
Shared dispositive power: 1,643,474.00
Aggregate excludes certain shares: N

Reporting person 5

Name: The Liliana Arsenio-Undavia 2018 Trust u/a Dated 10/25/2018
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 60,000.00
Shared voting power: 2,151,504.00
Sole dispositive power: 60,000.00
Shared dispositive power: 2,151,504.00
Aggregate excludes certain shares: N

Reporting person 6

Name: The Nilesh Undavia Irrevocable Family Trust #1
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 260,000.00
Shared voting power: 1,951,504.00
Sole dispositive power: 260,000.00
Shared dispositive power: 1,951,504.00
Aggregate excludes certain shares: N

Reporting person 7

Name: The Liliana Undavia Irrevocable Family Trust #1
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 260,000.00
Shared voting power: 1,951,504.00
Sole dispositive power: 260,000.00
Shared dispositive power: 1,951,504.00
Aggregate excludes certain shares: N

Reporting person 8

Name: The Kanta Undavia Revocable Trust
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 20,000.00
Shared voting power: 2,191,504.00
Sole dispositive power: 20,000.00
Shared dispositive power: 2,191,504.00
Aggregate excludes certain shares: N

Reporting person 9

Name: The Sophia Undavia Irrevocable Trust
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 7,000.00
Shared voting power: 2,204,504.00
Sole dispositive power: 7,000.00
Shared dispositive power: 2,204,504.00
Aggregate excludes certain shares: N

Reporting person 10

Name: The Jai Undavia Irrevocable Trust
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 7,000.00
Shared voting power: 2,204,504.00
Sole dispositive power: 7,000.00
Shared dispositive power: 2,204,504.00
Aggregate excludes certain shares: N

Reporting person 11

Name: The Julia Undavia Irrevocable Trust
No reporting person CIK indication: Y
Citizenship / organization: FL
Reporting person type: OO
Group designation: a
Source of funds code: OO
Legal proceedings indication: N
Aggregate amount owned: 2,211,504.00
Percent of class: 8.5
Sole voting power: 7,000.00
Shared voting power: 2,204,504.00
Sole dispositive power: 7,000.00
Shared dispositive power: 2,204,504.00
Aggregate excludes certain shares: N

Item 1

Issuer

GRAFTECH INTERNATIONAL LTD

Security title

Common Stock

Principal address

Comment

This Amendment No. 3 (this Amendment) amends and supplements the Schedule 13D originally filed with the Securities and Exchange Commission (the SEC) on February 12, 2024 (as amended, the Schedule 13D), by the Reporting Persons with respect to the common stock, par value $0.01 per share (the Common Stock), of GrafTech International Ltd., a Delaware corporation (the Issuer). Capitalized terms used but not defined in this Amendment have the meanings given to them in the Schedule 13D. Except as specifically amended by this Amendment, the Schedule 13D remains in full force and effect. On August 29, 2025, the Issuer effected a 1-for-10 reverse stock split of the Common Stock (the Reverse Stock Split). Unless otherwise indicated, all share figures in this Amendment reflect the Reverse Stock Split. The 17,308,942 shares of Common Stock reported in Amendment No. 2 correspond to 1,730,895 shares of Common Stock on a post-Reverse Stock Split basis.

Item 2

Principal business address

(b) Item 2(b) is hereby amended and restated in its entirety as follows: The business address of each Reporting Person is 474 NE 3rd Street, Boca Raton, FL 33432.

Item 3

Source of funds

Item 3 is hereby amended and restated in its entirety as follows: Personal funds of the Undavias, contributed to the Trusts and to Nilesh P Undavia Charles Schwab & Co., Inc. Custodial IRA Rollover (the Charles Schwab IRA) and Nilesh P Undavia IRA Rollover with JP Morgan (the JP Morgan IRA and, together with the Charles Schwab IRA, the IRAs), were used to purchase the 2,211,504 shares (the Shares) of the Issuers Common Stock to which this Schedule 13D relates. The Shares were purchased by the Reporting Persons for an aggregate purchase price of approximately $46,135,312.

Item 4

Purpose of transaction

Item 4 is hereby amended to add the following: The Reporting Persons acquired the additional Shares reported in this Amendment for investment purposes, based on their belief that the Common Stock is an attractive investment in light of current industry conditions. The Reporting Persons may acquire additional shares of Common Stock from time to time in open market transactions, privately negotiated transactions or otherwise, or may dispose of shares of Common Stock, in each case depending upon market conditions, the price and availability of the Common Stock, and other investment considerations, and in each case subject to the terms of the Cooperation Agreement described in the Schedule 13D.

Item 5

Number of shares

Mr. Undavia may be deemed to beneficially own through the IRAs (i) 620,000 shares of Common Stock beneficially owned by the Charles Schwab IRA and (ii) 402,474 shares of Common Stock beneficially owned by the JP Morgan IRA. Mr. Undavia is the sole trustee of the LU Irrev Trust. Accordingly, Mr. Undavia may be deemed to hold sole voting and dispositive power with respect to the 1,282,474 shares of Common Stock held by him through the IRAs and the LU Irrev Trust. Liliana Undavia is the sole trustee of the NU Irrev Trust, the Sophia Trust, the Jai Trust, and the Julia Trust. Accordingly, Liliana Undavia may be deemed to hold sole voting and dispositive power with respect to the 281,000 shares of Common Stock held by the NU Irrev Trust, the Sophia Trust, the Jai Trust, and the Julia Trust. Nilesh Undavia and Kanta Undavia are trustees of the Kanta Trust, each with power to vote or dispose of the shares of Common Stock held by such Trust unilaterally. Nilesh Undavia and Liliana Undavia are trustees of the NPU Trust and the LAU Trust, each with power to vote or dispose of the shares of Common Stock held by such Trusts unilaterally. Furthermore, the Reporting Persons have verbally agreed to vote, hold or sell the Shares in the same manner and to act in concert with respect to the proposals brought to the Board by Mr. Undavia as set forth in Item 4 and as brought forth by Mr. Undavia from time to time. Accordingly, each of the Reporting Persons could be deemed to have shared voting and dispositive power with respect to the following number of Shares: NPU Trust: 1,643,474 LAU Trust: 2,151,504 NU Irrev Trust: 1,951,504 LU Irrev Trust: 1,951,504 Kanta Trust: 2,191,504 Sophia Trust: 2,204,504 Jai Trust: 2,204,504 Julia Trust: 2,204,504 Nilesh Undavia: 929,030 Liliana Undavia: 1,930,504 Kanta Undavia: 2,211,504

Transactions

(c) Item 5(c) is hereby amended and restated in its entirety as follows: Except as set forth below, none of the Reporting Persons has effected any transactions in the Common Stock during the past 60 days. Each of the transactions set forth below was an open market purchase of Common Stock: The Liliana Arsenio-Undavia 2018 Trust u/a Dated 10/25/2018 Trade Date Number of Shares Price Per Share ($) Aggregate Purchase Price($) 09/08/2026 4,001 $6.72 $26,878.72 09/08/2026 999 $6.69 $6,679.31 09/08/2026 5,000 $6.69 $33,430.00 09/08/2026 5,000 $6.62 $33,087.17 09/08/2026 5,000 $6.50 $32,500.00 Total 20,000 $132,575.20 Nilesh Undavia (Charles Schwab IRA) Trade Date Number of Shares Price Per Share ($) Aggregate Purchase Price($) 09/09/2026 4,429 $6.27 $27,760.89 09/09/2026 571 $6.23 $3,556.95 09/09/2026 5,000 $6.15 $30,750.00 09/09/2026 5,000 $6.15 $30,749.52 09/09/2026 5,000 $6.15 $30,750.00 Total 20,000 $123,567.36 The Nilesh P Undavia 2018 Trust u/a Dated 10/25/2018 Trade Date Number of Shares Price Per Share ($) Aggregate Purchase Price($) 09/16/2026 225,419 $8.11 $1,827,484.22 09/16/2026 365 $7.36 $2,686.40 Total 225,784 $1,830,170.62

Percentage of class

The Reporting Persons beneficially own 2,211,504 Shares, or approximately 8.5%, of the outstanding Common Stock (calculated based on information included in the Quarterly Report on Form 10-Q filed by the Issuer on July 24, 2026 for the quarter ended June 30, 2026, which reported that 26,092,164 shares of Common Stock were issued and outstanding as of June 30, 2026). The Reporting Persons also may be deemed to be members of a 'group' (within the meaning of SEC Rule 13d-5) by virtue of their verbal agreement to vote, hold, or sell the Shares in the same manner and to act in concert with respect to the proposals brought to the Board by Mr. Undavia as set forth in Item 4 and as brought forth by Mr. Undavia from time to time.

Signature 1

Reporting person: Undavia Nilesh
Signed: /s/ Nilesh Undavia
Title: Nilesh Undavia, Individual
Date: 09/18/2026

Signature 2

Reporting person: Liliana Undavia
Signed: /s/ Liliana Undavia
Title: Liliana Undavia, Individual
Date: 09/18/2026

Signature 3

Reporting person: Kanta Undavia
Signed: /s/ Kanta Undavia
Title: Kanta Undavia, Individual
Date: 09/18/2026

Signature 4

Reporting person: The Nilesh P Undavia 2018 Trust u/a Dated 10/25/2018
Signed: /s/ Nilesh Undavia · /s/ Liliana Undavia
Title: Nilesh Undavia, Trustee · Liliana Undavia, Trustee
Date: 09/18/2026 · 09/18/2026

Signature 5

Reporting person: The Liliana Arsenio-Undavia 2018 Trust u/a Dated 10/25/2018
Signed: /s/ Liliana Undavia · /s/ Nilesh Undavia
Title: Liliana Undavia, Trustee · Nilesh Undavia, Trustee
Date: 09/18/2026 · 09/18/2026

Signature 6

Reporting person: The Nilesh Undavia Irrevocable Family Trust #1
Signed: /s/ Liliana Undavia
Title: Liliana Undavia, Trustee
Date: 09/18/2026

Signature 7

Reporting person: The Liliana Undavia Irrevocable Family Trust #1
Signed: /s/ Nilesh Undavia
Title: Nilesh Undavia, Trustee
Date: 09/18/2026

Signature 8

Reporting person: The Kanta Undavia Revocable Trust
Signed: /s/ Nilesh Undavia · /s/ Kanta Undavia
Title: Nilesh Undavia, Trustee · Kanta Undavia, Trustee
Date: 09/18/2026 · 09/18/2026

Signature 9

Reporting person: The Sophia Undavia Irrevocable Trust
Signed: /s/ Liliana Undavia
Title: Liliana Undavia, Trustee
Date: 09/18/2026

Signature 10

Reporting person: The Jai Undavia Irrevocable Trust
Signed: /s/ Liliana Undavia
Title: Liliana Undavia, Trustee
Date: 09/18/2026

Signature 11

Reporting person: The Julia Undavia Irrevocable Trust
Signed: /s/ Liliana Undavia
Title: Liliana Undavia, Trustee
Date: 09/18/2026

Company context

GrafTech International Ltd. is a leading manufacturer of high-quality graphite electrode products essential to the production of electric arc furnace steel and other ferrous and non-ferrous metals. The Company has a competitive portfolio of low-cost, ultra-high power graphite electrode manufacturing facilities, with some of the highest capacity facilities in the world. We are the only large-scale graphite electrode producer that is substantially vertically integrated into petroleum needle coke, our key raw material for graphite electrode manufacturing. This unique position provides us with competitive advantages in product quality and cost.

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