UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 4)¹

ARCA biopharma, Inc.

(Name of Issuer)

Common Stock, $0.001 par value

(Title of Class of Securities)

00211Y506

(CUSIP Number)

Jacob Ma-Weaver

Cable Car Capital LLC

2261 Market Street #4307

San Francisco, California 94114

(415) 857-1965

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

May 25, 2022

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

The following constitutes Amendment No. 4 to the Schedule 13D filed by the undersigned (“Amendment No. 4”). This Amendment No. 4 amends the Schedule 13D as specifically set forth herein.

Item 3 is hereby amended and restated to read as follows:

The Shares to which this Amendment No. 4 relates were acquired for an aggregate purchase price of $5,147,153 inclusive of brokerage commissions and net of premium received from written option contracts. Funds for the purchase were obtained from the available working capital of the Fund. Although the Fund has the ability to obtain margin loans in the ordinary course of its business, no part of the purchase price was obtained on margin or through any other borrowings.

The purpose of this Amendment No. 4 is to report a greater than 1% change in ownership of the Shares by the Reporting Persons.

Items 5 (a) – (c) are hereby amended and restated to read as follows:

(a)       The aggregate percentage of Common Stock reported owned by the Reporting Persons is based on 14,410,143 shares outstanding, as of April 29, 2022, which is the total number of shares outstanding as reported on the cover page of the Issuer’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 2, 2022. As of the close of business on May 11, 2022, the Fund beneficially owned 2,580,452 Shares. Cable Car, as the General Partner of the Fund, may be deemed the beneficial owner of the 2,580,452 Shares owned by the Fund. Mr. Ma-Weaver, as the Managing Member of Cable Car, may be deemed the beneficial owner of the 2,580,452 Shares owned by the Fund.

(b)       The Fund has sole voting and dispositive power over the shares reported herein.

(c)       The transactions in the Shares by the Fund since the filing of Amendment No. 3 to the Schedule 13D are set forth in Schedule A and are incorporated herein by reference. None of Cable Car or Mr. Ma-Weaver have entered into any transactions in the Shares since the filing of Amendment No. 3 the Schedule 13D. Each Reporting Person and Cable Car disclaims beneficial ownership of such Shares except to the extent of his or its pecuniary interest therein.

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: May 27, 2022

SCHEDULE A

TRANSACTIONS IN SECURITIES OF THE ISSUER
SINCE THE FILING OF AMENDMENT NO. 3 TO THE SCHEDULE 13D

¹ Represents a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $2.2650 to $2.2950, inclusive of brokerage commissions. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares purchased at each separate price within the range set forth in this footnote.

² Represents a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $2.2550 to $2.3050, inclusive of brokerage commissions. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares purchased at each separate price within the range set forth in this footnote.

³ Represents a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $2.2400 to $2.3050, inclusive of brokerage commissions. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares purchased at each separate price within the range set forth in this footnote.

⁴ Represents a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $2.2850 to $2.3050, inclusive of brokerage commissions. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares purchased at each separate price within the range set forth in this footnote.

⁵ Represents a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $2.2850 to $2.2950, inclusive of brokerage commissions. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares purchased at each separate price within the range set forth in this footnote.

⁶Represents a weighted average price. These Shares were purchased in multiple transactions at prices ranging from $2.2550 to $2.3450, inclusive of brokerage commissions. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of Shares purchased at each separate price within the range set forth in this footnote.