Western Standard SC 13G/A ARCA biopharma / Western Standard ownership change

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No. 1)*

ARCA biopharma, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class Securities)

00211Y506

(CUSIP Number)

December 31, 2023

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

☐ Rule 13d-1(b)

☒ Rule 13d-1(c)

☐ Rule 13d-1(d)

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 the disclosure provided in a prior cover page.

The information required in 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).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

	Page 2 of 9 Pages
CUSIP No. 00211Y506

1	NAMEOF REPORTING PERSONS.  I.R.S. IDENTIFICATION NOS.OFABOVEPERSONS (ENTITIESONLY).  Western Standard, LLC  26-2921385
2	CHECKTHE APPROPRIATE BOXIFA MEMBEROFA GROUP (SEE INSTRUCTIONS)  (A) ☐  (B) ☐
3	SEC USE ONLY
4	CITIZENSHIPOR PLACEOF ORGANIZATION  California
NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER  1,410,143 *
		6	SHARED VOTING POWER  0
		7	SOLE DISPOSITIVE POWER  1,410,143 *
		8	SHARED DISPOSITIVE POWER  0
9	AGGREGATE AMOUNT BENEFICIALLY OWNEDBY EACH REPORTING PERSON  1,410,143 *
10	CHECKIFTHE AGGREGATE AMOUNTIN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
11	PERCENTOF CLASS REPRESENTEDBY AMOUNTIN ROW (9)  9.8% *
12	TYPEOF REPORTING PERSON (SEE INSTRUCTIONS)  IA

* This cover page reports the beneficial ownership interest of Western Standard, LLC (“Western Standard”) in the Issuer’s Common Stock as of December 31, 2023. On April 3, 2024, all of the shares of the Issuer’s Common Stock that may be deemed beneficially owned by Western Standard were sold by the private funds managed by Western Standard (“Funds”) that directly held all of the reported shares of the Issuer’s Common Stock, including Western Standard Partners, L.P. (“WSP LP”).

	Page 3 of 9 Pages
CUSIP No. 00211Y506

1	NAMEOF REPORTING PERSONS.  I.R.S. IDENTIFICATION NOS.OFABOVEPERSONS (ENTITIESONLY).  Eric D. Andersen
2	CHECKTHE APPROPRIATE BOXIFA MEMBEROFA GROUP (SEE INSTRUCTIONS)  (A) ☐  (B) ☐
3	SEC USE ONLY
4	CITIZENSHIPOR PLACEOF ORGANIZATION  United States of America

NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH	5	SOLE VOTING POWER  1,410,143 *
	6	SHARED VOTING POWER  0
	7	SOLE DISPOSITIVE POWER  1,410,143 *
	8	SHARED DISPOSITIVE POWER  0

9	AGGREGATE AMOUNT BENEFICIALLY OWNEDBY EACH REPORTING PERSON  1,410,143 *
10	CHECKIFTHE AGGREGATE AMOUNTIN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
11	PERCENTOF CLASS REPRESENTEDBY AMOUNTIN ROW (9)  9.8% *
12	TYPEOF REPORTING PERSON (SEE INSTRUCTIONS)  IN, HC

* This cover page reports the beneficial ownership interest of Eric Andersen in the Issuer’s Common Stock as of December 31, 2023. On April 3, 2024, all of the shares of the Issuer’s Common Stock that may be deemed beneficially owned by Mr. Andersen as the managing member of Western Standard were sold by the Funds that directly held all of the reported shares of the Issuer’s Common Stock, including WSP LP.

	Page 4 of 9 Pages
CUSIP No. 00211Y506

1	NAMEOF REPORTING PERSONS.  I.R.S. IDENTIFICATION NOS.OFABOVEPERSONS (ENTITIESONLY).  Western Standard Partners, L.P.  26-2921468
2	CHECKTHE APPROPRIATE BOXIFA MEMBEROFA GROUP (SEE INSTRUCTIONS)  (A) ☐  (B) ☐
3	SEC USE ONLY
4	CITIZENSHIPOR PLACEOF ORGANIZATION  Delaware
NUMBER OF SHARES  BENEFICIALLY  OWNED BY EACH REPORTING PERSON WITH		5	SOLE VOTING POWER  1,108,669
		6	SHARED VOTING POWER  0
		7	SOLE DISPOSITIVE POWER  1,108,669
		8	SHARED DISPOSITIVE POWER  0
9	AGGREGATE AMOUNT BENEFICIALLY OWNEDBY EACH REPORTING PERSON  1,108,669
10	CHECKIFTHE AGGREGATE AMOUNTIN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS)
11	PERCENTOF CLASS REPRESENTEDBY AMOUNTIN ROW (9)  7.7%
12	TYPEOF REPORTING PERSON (SEE INSTRUCTIONS)  PN

* This cover page reports the beneficial ownership interest of WSP LP in the Issuer’s Common Stock as of December 31, 2023. On April 3, 2024, WSP LP sold all of its shares of the Issuer’s Common Stock.

Page 5 of 9 Pages

Item 1.

(a) Name of Issuer

ARCA biopharma, Inc.

(b) Address of Issuer’s Principal Executive Offices

10170 Church Ranch Way, Suite 100, Westminster, CO, 80021

Item 2.

(a) Name of Person Filing

This Schedule 13G is being filed on behalf of Western Standard, LLC, Eric D.

Andersen, and Western Standard Partners, L.P. (each, a “Reporting Person”).

(b) Address of Principal Business office or, if None, Residence

For each Reporting Person,

5757 Wilshire Blvd, Suite 636, Los Angeles, California 90036

(c) Citizenship

Western Standard, LLC is a California limited liability company

Western Standard Partners, L.P. is a Delaware limited partnership

Mr. Andersen is a United States citizen

(d) Title of Class of Securities

Common Stock, par value $0.001 per share

(e) CUSIP Number

00211Y506

Item 3. If this statement is filed pursuant to §§ 240.13d-1(b), or 240.13d-2(b) or (c), check whether the person filing is a:

(a)	☐	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78c).
(b)	☐	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).
(c)	☐	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).
(d)	☐	Investment company registered under section 8 of the Investment Company Act (15 U.S.C. 80a-8).
(e)	☐	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E).

Page 6 of 9 Pages

(f)	☐	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(ii)(F).
(g)	☐	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G).
(h)	☐	A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813).
(i)	☐	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3).
(j)	☐	Group in accordance with § 240.13d-1(b)(ii)(J).

Item 4. Ownership

For each of Western Standard, LLC and Eric A. Andersen: **

(a) Amount beneficially owned: 1,410,143

(b) Percent of class: 9.8% *

(c) Number of shares to which the Reporting Person has:

(i) Sole power to vote or to direct the vote: 1,410,143

(ii) Shared power to direct the vote: 0

(iii) Sole power to dispose or to direct the disposition of: 1,410,143

(iv) Shared power to dispose or to direct the disposition of: 0

For each of Western Standard Partners, L.P.:

(a) Amount beneficially owned: 1,108,669

(b) Percent of class: 7.7%*

(c) Number of shares to which the Reporting Person has:

(i) Sole power to vote or to direct the vote: 1,108,669

(ii) Shared power to direct the vote: 0

(iii) Sole power to dispose or to direct the disposition of: 1,108,669

(iv) Shared power to dispose or to direct the disposition of: 0

* The shares of the Common Stock reported in this Schedule 13G represent the shares of Common Stock beneficially owned by the Reporting Persons as of December 31, 2023. Percentage calculated based on 14,410,143 shares of Common Stock outstanding as of December 6, 2023, as reported in the issuer’s most recent Proxy Statement on Schedule 14A, as filed with the Securities and Exchange Commission on December 19, 2023.

** Western Standard, LLC, in its capacity as investment adviser to Western Standard Partners, L.P. and another private investment fund (the “Funds”), may be deemed to beneficial own the shares of the Issuer’s Common Stock (the “Shares”) owned by the Funds due to its power to direct the disposition and voting of the Shares owned by the Funds. Eric D. Andersen is the Managing Member of Western Standard, LLC and may also be deemed to beneficially own the Shares owned by the Funds. Pursuant to Rule 13d-4, each of Western Standard LLC and Eric D. Andersen disclaims beneficial ownership of the securities owned by the Funds, except to the extent of its or his pecuniary interest in the Shares.

Page 7 of 9 Pages

Item 5. Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class securities, check the following  ☒

On April 3, 2024, the Reporting Persons ceased to beneficially own more than 5% of the Issuer’s Common Stock following the sale of all of the Shares held by the Funds.

Item 6. Ownership of More than Five Percent on Behalf of Another Person.

Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company.

Item 8. Identification and Classification of Members of the Group.

Item 9. Notice of Dissolution of Group.

Item 10. Certification:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

Page 8 of 9 Pages

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.

Date: April 5, 2024

Western Standard Partners, L.P.
By: Western Standard, LLC, its General Partner
By:	/s/ Eric D. Andersen
	Eric D. Andersen, Managing Member
Western Standard, LLC
By:	/s/ Eric D. Andersen
	Eric D. Andersen, Managing Member
	/s/ Eric D. Andersen
	Eric D. Andersen

Page 9 of 9 Pages

Exhibit A

Joint Filing Agreement Pursuant to Rule 13d-1

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), the undersigned hereby agree to the joint filing on behalf of each of them of a Statement on Schedule 13G (including any and all amendments thereto, the “Schedule 13G”) relating to the Common Stock, $0.001 par value per share, of ARCA biopharma Inc., which may be deemed necessary pursuant to Regulation 13D or 13G promulgated under the Exchange Act.

The undersigned further agree that each party hereto is responsible for the timely filing of the Schedule 13G, and for the accuracy and completeness of the information concerning such party contained therein; provided, however, that no party is responsible for the accuracy or completeness of the information concerning any other party, unless such party knows or has a reason to believe that such information is inaccurate.

It is understood and agreed that a copy of this Joint Filing Agreement shall be attached as an exhibit to the Schedule 13G, filed on behalf of each of the parties hereto.

Date: April 5, 2024

Western Standard Partners, L.P.
By: Western Standard, LLC, its General Partner
By:	/s/ Eric D. Andersen
	Eric D. Andersen, Managing Member
Western Standard, LLC
By:	/s/ Eric D. Andersen
	Eric D. Andersen, Managing Member
	/s/ Eric D. Andersen
	Eric D. Andersen