Company: IPGP
Filing Date: 2025-04-07
Form Type: DEFA14A
Source: 0001111928-25-000056
Chunk: 0

Company: IPG PHOTONICS CORP
Filing Date: 2025-04-07
Form: DEFA14A
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549
<div align='center'>(Rule 14a-101)</div>

#### SCHEDULE 14A

#### Proxy Statement Pursuant to Section 14(a) of the
<div align='center'>Securities Exchange Act of 1934 (Amendment No.__ )</div>

| þ |     | Filed by the Registrant |     | ¨ |     | Filed by a Party other than the Registrant |

| CHECK THE APPROPRIATE BOX: |     |                                                                                 |
| ¨                          |     | Preliminary Proxy Statement                                                     |
| ¨                          |     | Confidential, For Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
| ¨                          |     | Definitive Proxy Statement                                                      |
| þ                          |     | Definitive Additional Materials                                                 |
| ¨                          |     | Soliciting Material Pursuant to Section 240.14a-12                              |

#### IPG Photonics Corporation
<div align='center'>(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)</div>

| Payment of Filing Fee (Check all boxes that apply): |     |                                                                                                     |
| þ                                                   |     | No fee required.                                                                                    |
| ¨                                                   |     | Fee paid previously with preliminary materials.                                                     |
| ¨                                                   |     | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |