Company: PRME
Filing Date: 2025-11-07
Form Type: S-3ASR
Source: 0001628280-25-050428
Chunk: 1

Company: Prime Medicine, Inc.
Filing Date: 2025-11-07
Form: S-3ASR
Chunk 1
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 box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.D or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☒

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

| Large accelerated filer |     | ☐ |     | Accelerated filer         |     | ☐ |
| Non-accelerated filer   |     | ☒ |     | Smaller reporting company |     | ☒ |
|                         |     |   |     | Emerging growth company   |     | ☒ |

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

### EXPLANATORY NOTE
We are filing this registration statement with the Securities and Exchange Commission (the “SEC”) using a “shelf” registration process to replace our prior registration statement on Form S-3 (File No. 333-275321) (the “Prior Registration Statement”) that will expire on November 13, 2026, in accordance with applicable SEC regulations. In accordance with Rule 415(a)(6) under the Securities Act of 1933, as amended (the “Securities Act”), the offering of securities under the Prior Registration Statement will be deemed terminated as of the date of effectiveness of this registration statement.

This registration statement contains two prospectuses:

• a base prospectus that covers the offering, issuance and sale by us of our common stock, preferred stock, debt securities, warrants and/or units; and

• a sales agreement prospectus that covers the offer and sale by us