Company: CYTK
Filing Date: 2025-02-27
Form Type: S-3ASR
Source: 0001193125-25-039426
Chunk: 42

Company: CYTOKINETICS INC
Filing Date: 2025-02-27
Form: S-3ASR
Chunk 42
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 supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense.

Jefferies

The date of this prospectus supplement is February 27, 2025.

TABLE OF CONTENTS

|                                                   |     | Page |      |
| ABOUT THIS PROSPECTUS SUPPLEMENT                  |     |      | S-1  |
| PROSPECTUS SUPPLEMENT SUMMARY                     |     |      | S-2  |
| THE OFFERING                                      |     |      | S-3  |
| RISK FACTORS                                      |     |      | S-4  |
| SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS |     |      | S-6  |
| USE OF PROCEEDS                                   |     |      | S-8  |
| DILUTION                                          |     |      | S-9  |
| PLAN OF DISTRIBUTION                              |     |      | S-11 |
| LEGAL MATTERS                                     |     |      | S-13 |
| EXPERTS                                           |     |      | S-13 |
| WHERE YOU CAN FIND MORE INFORMATION               |     |      | S-14 |
| INCORPORATION OF CERTAIN INFORMATION BY REFERENCE |     |      | S-15 |

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ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement is part of an automatic shelf registration statement that we have filed with the Securities and Exchange
Commission, or the SEC, as a “well-known seasoned issuer” as defined in Rule 405 under the Securities Act utilizing a “shelf” registration process. Under the shelf registration statement, we may sell an unspecified amount of
securities from time to time. Under this prospectus supplement, we may offer shares of our common stock having an aggregate offering price of up to $500.0 million from time to time at prices and on terms to be determined by market conditions at
the time of offering.

We provide information to you about this offering of shares of our common stock in two separate documents that are
bound together: (1) this prospectus supplement, which describes the specific details regarding this offering; and (2) the accompanying prospectus, which provides general information, some of which may not apply to this offering. Generally,
when we refer to this “prospectus,” we are referring to both documents combined. This prospectus supplement describes the terms of this offering of common stock and also adds to and updates information contained in the documents
incorporated by reference into this prospectus supplement