Company: CYTK
Filing Date: 2025-02-27
Form Type: S-3ASR
Source: 0001193125-25-039426
Chunk: 52

Company: CYTOKINETICS INC
Filing Date: 2025-02-27
Form: S-3ASR
Chunk 52
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 net tangible book value per share to new investors in this offering to $3.84 per share, after deducting commissions and estimated offering expenses payable by us. This information is supplied for illustrative purposes only and may differ based on the actual offering price and the actual number of shares offered. The above discussion and table are based on 118,209,139 shares outstanding as of December 31, 2024, and exclude as of that date:

| • |     | 10,419,523 shares of common stock underlying options outstanding at a weighted average exercise price of $31.84 
 per share;                                                                                                      |

| • |     | 1,865,058 shares of common stock underlying restricted stock units and performance stock units outstanding; |

S-9

| • |     | 12,575,140 shares reserved for future issuance pursuant to the conversion of our outstanding convertible senior 
 notes; and                                                                                                      |

| • |     | 5,326,506 shares of common stock available for future grant of equity awards under our equity incentive plans, 
 including our employee stock purchase plan.                                                                    |

To the extent that options outstanding as of December 31, 2024 have been or may be exercised, restricted or performance stock units settled, or other shares issued, investors purchasing our common stock in this offering may experience further dilution. In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders. S-10

PLAN OF DISTRIBUTION

We have entered into the Sales Agreement, with Jefferies relating to the sale of shares of our common stock. In accordance with the terms of
the Sales Agreement, we may offer and sell up to $500.0 million of our shares of common stock from time to time through Jefferies acting as agent pursuant to this prospectus supplement and the accompanying prospectus. Sales of our shares of
common stock, if any, under this prospectus supplement and the accompanying prospectus will be made by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) under the Securities Act.

Each time we wish to issue and sell our shares of common stock under the sales agreement, we will notify Jefferies of the number of shares to