Company: ANY
Filing Date: 2025-12-05
Form Type: DEFA14A
Source: 0001591956-25-000026
Chunk: 0

Company: Sphere 3D Corp.
Filing Date: 2025-12-05
Form: DEFA14A
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### SCHEDULE 14A

#### PROXY STATEMENT PURSUANT TO SECTION 14(a)

#### OF THE SECURITIES EXCHANGE ACT OF 1934
Filed by the Registrant x Filed by a Party other than the Registrant o

Check the appropriate box:

| o |     | Preliminary Proxy Statement                                                     |
| o |     | Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
| o |     | Definitive Proxy Statement                                                      |
| x |     | Definitive Additional Materials                                                 |
| o |     | Soliciting Material Pursuant to §240.14a-11(c) or §240.14a-12                   |

| Sphere 3D Corp.                                                          |     |                                                                                                     |
| (Name of Registrant as Specified in its Charter)                         |     |                                                                                                     |
| (Name of Person(s) Filing Proxy Statement, if other than the Registrant) |     |                                                                                                     |
| Payment of Filing Fee (Check all boxes that apply):                      |     |                                                                                                     |
| x                                                                        |     | No fee required                                                                                     |
| o                                                                        |     | Fee paid previously with preliminary materials                                                      |
| o                                                                        |     | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

### IMPORTANT NOTICE REGARDING

### INTERNET AVAILABILITY OF PROXY MATERIALS
<div align='center'>for the Sphere 3D Corp.

Special Meeting of Shareholders</div>

#### Meeting

#### Details
<div align='center'>Thursday, January 15, 2026

11:30AM Eastern Time

https://Virtual-Meetings.TSXTrust.com/1862

Password: sphere3d2026 (case sensitive)

Get</div>

#### Informed
<div align='center'>Before You Vote

View the Notice of Meeting & Proxy Statement online at</div>

#### HTTPS://DOCS.TSXTRUST.COM/2040

#### OR
You can receive a free paper or email copy of the materials by requesting prior to January 7, 2026. Unless requested, you will not receive a paper or email copy. If you would like to request a copy of the materials for this and/or future shareholder meetings