ARCA biopharma : Amendment to Bylaws (Form 8-K)

Amendment to Bylaws

On June 28, 2021, the Board of Directors of ARCA biopharma, Inc. (the 'Company') approved an amendment (the 'By-Law Amendment') to Article II, Section 7 of the Company's amended and restated by-laws (the 'By-Laws') to reduce the number of shares present at a meeting of stockholders necessary to constitute a quorum to conduct business from a majority of issued and outstanding shares to one-third (1/3) of issued and outstanding shares.

On April 21, 2021, the Company filed with the Securities and Exchange Commission a definitive joint proxy statement (the 'Proxy Statement') with respect to the annual meeting of the Company's stockholders commenced on June 10, 2021 and adjourned until July 8, 2021.

Supplemental Disclosures to the Proxy Statement

This Current Report on Form 8-K (this 'Form 8-K) is being filed to update and supplement the Proxy Statement. The information contained in this Form 8-K is incorporated by reference into the Proxy Statement. Terms used in this Form 8‑K, but not otherwise defined, shall have the meanings ascribed to such terms in the Proxy Statement.

The following section of the Proxy Statement is amended as follows:

What is the quorum requirement?

A quorum of stockholders is necessary to hold a valid meeting. A quorum will be present if stockholders holding a majority33 1/3%of the outstanding shares entitled to vote are present at the meeting in person or represented by proxy. On the record date, April 9, 2021, there were 14,410,143 shares of Common Stock outstanding and entitled to vote. Thus, the holders of 7,205,0724,803,381shares of Common Stock must be present at the meeting in person or represented by proxy at the meeting to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your broker, bank or other nominee) or if you vote in person at the meeting. Abstentions and broker non-votes, if any, will be counted towards the quorum requirement. If there is no quorum, the holders of a majority33 1/3%of shares present at the meeting in person or represented by proxy may adjourn the meeting to another date.