UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No. )

Filed by the Registrant ☐

Filed by a Party other than the Registrant ☒

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☐ Definitive Proxy Statement

☒ Definitive Additional Materials

☐ Soliciting Material Under § 240.14a-12

ARGO GROUP INTERNATIONAL HOLDINGS, LTD.

(Name of Registrant as Specified In Its Charter)

CAPITAL RETURNS MASTER, LTD.

CAPITAL RETURNS MANAGEMENT, LLC

THE CAPITAL RETURNS 2016 FAMILY TRUST

RONALD D. BOBMAN

DAVID W. MICHELSON

(Name of Persons(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☒ No fee required

☐ Fee paid previously with preliminary materials

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

Capital Returns Master, Ltd., a Cayman Islands exempted company, together with the other participants named herein (collectively, “Capital Returns”), has filed a definitive proxy statement and accompanying WHITE universal proxy card with the Securities and Exchange Commission in connection with the 2022 annual general meeting of shareholders (the “Annual General Meeting”) of Argo Group International Holdings, Ltd., a Bermuda exempted company limited by shares (the “Company”), to be used to solicit votes for the election of Capital Returns’ slate of highly qualified nominees at the Annual General Meeting.

Capital Returns has delivered the following materials to shareholders of the Company: 

IMPORTANT VOTING INSTRUCTIONS FOR ARGO SHAREHOLDERS:

VOTE BY INTERNET OR MAIL

Due to new rules implemented by the SEC, our two nominees will also appear on the Company’s blue proxy card and blue voting instruction form. This means you can vote for needed change at ARGO by voting for our nominees on either the Company’s blue voting instruction form or the enclosed WHITE voting instruction form from Capital Returns. But remember only your latest dated vote actually counts.

VOTING BY INTERNET IS QUICK & EASY!

1) Go to www.proxyvote.com

2) Use the 16-digit control number located on the enclosed WHITE voting instruction form.

PLEASE FOLLOW THESE INSTRUCTIONS IF VOTING BY MAI L

1) We recommend you vote “FOR” the two Capital Returns nominees and the five Acceptable Company nominees we do not oppose. Please do not mark a vote “FOR” more than seven nominees or your vote will be invalidated on the Director proposal. (Proposal 1)

2) You may also vote “FOR” less than seven nominees, but you must affirmatively mark a “FOR” vote on whichever Director nominees you support, or your vote will default to a withhold vote.

3) Only your latest dated vote counts. If you didn’t already vote for either or our nominees on the Company’s blue voting instruction form, a later dated vote on enclosed WHITE voting instruction form will revoke your previously cast vote.

4) While you may vote for our two nominees on the Company’s blue voting instruction form, we still recommend that you vote each and every WHITE voting instruction form you receive since you may own more than one account.