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:

Vicor Corporation

(Name of Registrant as Specified In Its Charter)

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

April 29, 202030, 2021

Dear Stockholder:

You are cordially invited to attend the 20202021 Annual Meeting of Stockholders (the “Annual Meeting”) of Vicor Corporation (the “Corporation”). The Annual Meeting will be held virtually at the following date time, and location:time:

Due to the continued public health precautions associated with the COVID-19 pandemic, the Corporation will hold a virtual Annual Meeting conducted via live audio webcast in order to protect the health and well-being of its stockholders, employees and directors. The Annual Meeting will take place as a virtual meeting only, and neither stockholders nor guests will be able to attend the Annual Meeting in person. We believe that hosting a virtual meeting will facilitate stockholder attendance and participation at the Annual Meeting by enabling stockholders to participate remotely from any location. We have designed the format of the virtual Annual Meeting so that stockholders have the same rights and opportunities to vote and participate as they would have at a physical meeting. Stockholders will be able to submit questions before and during the meeting using online tools, providing stockholders with the opportunity for meaningful engagement with the Corporation. For instructions on attending the virtual Annual Meeting and voting your shares, please see the attached Notice of Annual Meeting and Proxy Statement.

The attached Notice of Annual Meeting and Proxy Statement cover the formal business of the Annual Meeting and contain a discussion of the matters to be voted upon at the Annual Meeting. At the Annual Meeting, the Corporation’s management also will report on the operations of the Corporation and be available to respond to appropriate questions from stockholders.

We hope you will be able to attend the Annual Meeting, but in any event we would appreciate your completing, dating, signing, and returning your Proxy Card(s) as promptly as possible. If you attend the Annual Meeting and wish to vote your shares, in person, you may revoke your proxy at that time.

Sincerely yours,

PATRIZIO VINCIARELLI

Chairman of the Board, President and

Chief Executive Officer

VICOR CORPORATION

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON FRIDAY, JUNE 26, 202025, 2021

NOTICE IS HEREBY GIVEN that the 20202021 Annual Meeting of Stockholders (the “Annual Meeting”) of Vicor Corporation, a Delaware corporation (the “Corporation”), will be held on Friday, June 26, 2020,25, 2021, at 9:00 a.m., local time,Eastern Time. The Annual Meeting will be a completely virtual meeting conducted via live audio webcast. You will be able to attend the Annual Meeting as well as vote your shares, submit your questions and examine our stockholder list during the live audio webcast of the meeting by visiting http://www.meetingcenter.io/209784887,password “VICR2021,” and entering the 15-digit control number included on your proxy card or in the instructions that accompanied your proxy materials. For additional instructions on how to attend the Annual Meeting and vote your shares at the offices of Foley & Lardner LLP, 111 Huntington Avenue, Boston, Massachusetts 02199,Annual Meeting, see the information in the accompanying proxy statement.

The Annual Meeting is being held for the following purposes:

Any action may be taken on the foregoing matters at the Annual Meeting on the date specified above, or on any date or dates to which, by original or later adjournment, the Annual Meeting may be adjourned or to which the Annual Meeting may be postponed.

The Board of Directors has fixed the close of business on April 30, 2020,2021, as the record date for determining the stockholders entitled to receive notice of and to vote at the Annual Meeting and any adjournments or postponements thereof. Only stockholders of record at the close of business on April 30, 20202021 will be entitled to receive notice of and to vote at the Annual Meeting and any adjournments or postponements thereof.

You are requested to authorize a proxy to vote your shares by completing, dating, and signing the enclosed Proxy Card(s), which is being solicited by the Board of Directors, and by mailing it promptly in the enclosed postage-prepaid envelope. Any proxy may be revoked by delivering a written revocation to the Corporation’s Secretary stating that the proxy is revoked or by delivery of a properly executed, later dated proxy. Stockholders of record who attend the Annual Meeting may vote in person by notifying our Corporate Secretary, even if they have previously delivered a signed Proxy Card.

By Order of the Board of Directors

James A. SimmsRichard J. Nagel Jr.

Interim Corporate Secretary

Andover, Massachusetts

April 29, 202030, 2021

VICOR CORPORATION

25 FRONTAGE ROAD

ANDOVER, MASSACHUSETTS 01810

TELEPHONE(978) 470-2900

PROXY STATEMENT

FOR THE 20202021 ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD ON FRIDAY, JUNE 26, 202025, 2021

April 29, 202030, 2021

This Proxy Statement is furnished in connection with the solicitation of proxies by the Board of Directors (the “Board” and each member thereof, a “Director”) of Vicor Corporation (the “Corporation”, “Vicor”, “we”, “us”, or “our”) from owners of the outstanding shares of Common Stock and Class B Common Stock of the Corporation (each, a “Stockholder” and collectively, the “Stockholders”) for use at the 20202021 Annual Meeting of Stockholders (the “Annual Meeting”) of the Corporation and any adjournments or postponements thereof.

This Proxy Statement, the Notice of Annual Meeting, and the Proxy Card(s) (together, the “Proxy Solicitation Materials”) are first being mailed to Stockholders of record on or about May 7, 2021. The Corporation’s 2020 Annual Report on Form 10-K (the “Annual Report”), including financial statements for the fiscal year ended December 31, 2020, will be mailed to Stockholders concurrently with this Proxy Statement. The Annual Report, however, is not part of the Proxy Solicitation Materials.

GENERAL INFORMATION ABOUT THE ANNUAL MEETING AND VOTING

When and where will the Annual Meeting be held?

The Annual Meeting will be held on Friday, June 26, 2020,25, 2021, at 9:00 a.m., local time, at the offices of Foley & Lardner LLP, 111 Huntington Avenue, Boston, Massachusetts 02199,Eastern Time and at any adjournments or postponements thereof. AtThe Annual Meeting will be a completely virtual meeting conducted via live audio webcast.

How can I participate in the Annual Meeting?

To participate in the Annual Meeting, Stockholdersplease visit http://www.meetingcenter.io/209784887 and enter your name and email address and the password “VICR2021.” The Annual Meeting will begin promptly at 9:00 a.m., Eastern Time. We encourage you to access the meeting prior to the start time and to allow ample time for check-in procedures. We suggest beginning the online check-in process by 8:45 a.m., Eastern Time. You will need to obtain your own Internet access if you choose to attend the Annual Meeting online and/or vote over the Internet.

If you wish to vote, submit questions, and/or examine our Stockholder list during the Annual Meeting, you will need to enter your 15-digit control number.

If you are the Stockholder of record with respect to your shares, you can find your 15-digit control number on your Proxy Card.

If you hold your shares in street name (i.e., through an intermediary, such as a bank, broker or other nominee), you must register in advance to participate in the Annual Meeting and obtain your 15-digit control number. To register, you must obtain a legally valid proxy reflecting your holdings from your intermediary. A copy of the proxy, along with your name and email address, must be askedsubmitted to considerComputershare as follows:

Requests for registration must be received no later than 5:00 p.m., Eastern Time, on Friday, June 18, 2021. You will receive an email confirmation from Computershare, which will include your 15-digit control number.

Please note that if you hold your shares in street name and request a legally valid proxy from your intermediary, you will revoke any prior instructions provided to your intermediary as to how to vote your shares at the Annual Meeting. Accordingly, if you request a legally valid proxy from your intermediary, you must vote at the Annual Meeting in order for your vote to be recorded.

If you lose your 15-digit control number, you may join the Annual Meeting as a “Guest” but you will not be able to vote, submit questions or access our Stockholder list.

What is the difference between being a “Stockholder of record” and holding shares in “street name”?

A Stockholder of record (also called a “registered holder”) holds shares in his or her name. A Stockholder of record may or may not hold physical share certificates, but the shares owned by such a Stockholder are registered with our transfer agent under the Stockholder’s name.

Shares held in “street name” means that shares are held in the name of a bank, broker or other nominee on the holder’s behalf.

What is the purpose of the Annual Meeting?

The purpose of the Annual Meeting is to vote on the proposals set forthfollowing proposal, as described in this Proxy StatementStatement:

In this Proxy Statement, we referWe do not know of any matters to Vicor Corporation as “Vicor,” “the Corporation,” “we,” “us,” or “our.” In addition,be properly presented at the term “Proxy Solicitation Materials” includes this Proxy Statement, the Notice of Annual Meeting other than the proposal referred to above. If other matters are properly presented at the Annual Meeting or any adjournment or postponement thereof for consideration, and the Proxy Cards.

The Proxy Solicitation Materialsyou are first being mailed to Stockholdersa Stockholder of record and have submitted a proxy card, the persons named in your proxy card will have the discretion to vote on or about May 8, 2020. those matters for you.

Who is entitled to vote at the Annual Meeting?

The Board has fixed the close of business on April 30, 20202021 as the record date for the determination of Stockholders entitled to receive notice of and to vote at the Annual Meeting (the “Record Date”). Only Stockholders of record at the close of business on the Record Date will be entitled to receive notice of and to vote at the Annual Meeting.

As of March 31, 2020,2021, there were 28,903,41931,762,312 shares of Common Stock and 11,758,218 shares of Class B Common Stock of the Corporation outstanding and entitled to vote. Each share of Common Stock entitles the holder thereof to one vote per share (for an aggregate of 28,903,41931,762,312 votes or approximately 20%21% of the total voting power), and each share of Class B Common Stock entitles the holder thereof to 10 votes per share (for an aggregate of 117,582,180 votes or approximately 80%79% of the total voting power).Shares of Common Stock and Class B Common Stock will vote together as a single class, reflecting their respective voting entitlement, on each proposal at the Annual Meeting.

Stockholders are requested to complete, date, sign, and return the accompanying Proxy Card(s) in the enclosed postage-prepaid envelope. Shares represented by a properly executed Proxy Card received prior to the vote at the Annual Meeting and not revoked will be voted at the Annual Meeting as directed on the Proxy Card. If a properly executed Proxy Card is submitted and no instructions are given, the shares so represented will be voted FOR each of the Director nominees and FOR the approval of the compensation of the Corporation’s named executive officers. We do not anticipate any matters other than those set forth in this Proxy Statement will be presented at the Annual Meeting. If other matters are properly presented, proxies will be voted in accordance with the discretion of the proxy holders.

A Stockholder of record may revoke a proxy at any time before it has been exercised by: (1) delivering a written revocation to our Corporate Secretary, James A. Simms, at the address of the Corporation set forth above; (2) delivering a duly executed Proxy Card bearing a later date; or (3) appearing in person, notifying the Corporate Secretary of such revocation, and voting by ballot at the Annual Meeting. Any Stockholder of record as of the Record Date attending the Annual Meeting may vote in person whether or not a proxy has been previously submitted, but the presence (without further action) of a Stockholder at the Annual Meeting will not constitute revocation of a previously submitted proxy.2

How many shares must be present to hold the Annual Meeting?

The presence, in person (by virtual presence online) or by proxy, of Stockholders representing a majority in interest of all Common Stock and Class B Common Stock issued, outstanding, and entitled to vote at the Annual Meeting shall constitute a quorum for the transaction of business at the Annual Meeting. Because of his ownership of shares of Class B Common Stock and shares of Common Stock as of March 31, 2020,2021, which is expected to represent 81.5%80.4% of the total voting power at the Annual Meeting, a quorum is assured by the presence of Dr. Patrizio Vinciarelli, Chairman of the Board, President, and Chief Executive Officer, who will preside over the Annual Meeting. Shares that reflect abstentions will be counted for purposes of determining whether a quorum is present for the transaction of business at the Annual Meeting. Brokers

What are “broker non-votes”?

A “broker non-vote” occurs when shares held by a broker in “street name” for a beneficial owner are not voted with respect to a proposal because (1) the broker has not received voting instructions from the Stockholder who beneficially owns the shares and other nominees do not have discretionary voting power(2) the broker lacks the authority to vote the shares at their discretion. Proposal One is considered a non-discretionary matter, and a broker will lack the authority to vote uninstructed shares at their discretion on such proposal.

How do I vote my shares without attending the Annual Meeting?

We recommend that Stockholders vote by proxy even if they plan to attend the Annual Meeting and vote electronically. If you are a Stockholder of Common Stockrecord, there are two ways to vote:

Internet voting facilities for Stockholders of record will be available 24 hours a day and will close once the polls close during the Annual Meeting.

If your shares are held in street name, you will receive instructions on how to vote from your intermediary. You must follow the instructions of such intermediary in order for your shares to be voted.

How can I vote at the Annual Meeting?

If you wish to vote during the Annual Meeting, you will need to enter your 15-digit control number. See “How can I participate in the Annual Meeting?” above for additional information on obtaining your 15-digit control number. Stockholders may vote during the Annual Meeting by following the instructions available on the meeting website during the Annual Meeting.

Can I revoke or change my vote after I submit my proxy?

Yes. Whether you have voted by Internet or mail, if you are a Stockholder of record, you may change your vote and revoke your proxy by:

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If you hold shares in street name, you may submit new voting instructions by contacting your intermediary. You may also change your vote or revoke your proxy online at the Annual Meeting without instructionsif you obtain a signed proxy from the beneficial owners or persons entitledintermediary giving you the right to vote such sharesthe shares.

Your most recent Proxy Card or Internet proxy is the one that is counted. Your attendance at the Annual Meeting by itself will not revoke your proxy unless you give written notice of revocation to the Corporation before your proxy is voted or you vote online at the Annual Meeting.

Will there be a question and answer session during the Annual Meeting?

As part of the Annual Meeting, we will hold a live Q&A session. Only Stockholders that have accessed the Annual Meeting using a 15-digit control number (rather than as a “Guest”) by following the procedures outlined above in “How can I participate in the Annual Meeting?” will be permitted to submit questions during the Annual Meeting. Questions may be submitted during the Annual Meeting or in advance via email to invrel@vicr.com no later than 5:00 p.m. (Eastern Time), on any matter.Friday, June 18, 2021. Questions submitted in advance via email must include “Annual Meeting Question” in the subject line and include the Stockholder’s 15-digit control number. Questions unrelated to the purposes of the Annual Meeting or otherwise considered by Vicor to be inappropriate for the Annual Meeting will not be addressed.

What if I have trouble accessing the Annual Meeting virtually?

The virtual meeting platform is fully supported across MS Edge, Firefox, Chrome and Safari browsers and devices (desktops, laptops, tablets and cell phones) running the most up-to-date version of applicable software and plugins. Internet Explorer is no longer supported. Participants should ensure that they have a strong WiFi connection wherever they intend to participate in the Annual Meeting. We encourage you to access the Annual Meeting prior to the start time. A link on the meeting page will provide further assistance should you need it or you may call 1-888-724-2416 or 1-781-575-2748.

Who will pay for the cost of solicitationthis proxy solicitation?

The Corporation will pay the cost of proxies in the form enclosed herewith will be borne by the Corporation.soliciting proxies. In addition to the solicitation of proxies by mail, Directors, officers, and employees of the Corporation also may solicit proxies personally or by telephone,e-mail, or other form of electronic communication without special compensation for such activities. The Corporation also will request those intermediaries holding shares in their names or in the names of their nominees that are beneficially owned by others to forward proxy materials to and obtain proxies from such beneficial owners. The Corporation will reimburse such holdersintermediaries for their reasonable expenses in connection therewith.

The Corporation’s 2019 Annual Report on Form10-K (the “Annual Report”), including financial statements for the fiscal year ended December 31, 2019, will be mailed to Stockholders concurrentlyIf I share my residence with this Proxy Statement. The Annual Report, however, is not partanother Stockholder, how many copies of the Proxy Solicitation Materials. annual report and proxy statement should I receive?

The Corporation and certain intermediaries (e.g., banks, brokers, and nominees) may deliver only one copy of the Annual Report and Proxy Solicitation Materials to Stockholders sharing an address. The Corporation will deliver promptly, upon written or oral request, a separate copy of the Annual Report or Proxy Solicitation Materials, as applicable, to a Stockholder at a shared address. In order to receive such a separate document, please contact our Corporate Secretary, Mr. Simms, at the address of the Corporation set forth above. If Stockholders sharing an address (i) currently receive a single copy of the Annual Report and Proxy Solicitation Materials and wish to receive separate copies of such materials in the future or (ii) currently receive separate copies of the Annual Report and Proxy Solicitation Materials and wish to receive a single copy of such materials in the future, please contact Mr. Simms, our Corporate Secretary, or the applicable intermediary, as the case may be.

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PROPOSAL ONE

ELECTION OF EIGHTNINE DIRECTORS

In accordance with the requirements of theCorporation’s By-Laws, the Board recommends the number of Directors be fixed at eightnine and has nominated all of the Nominees named below for election to the Board. All of the Nominees except Mr. Ansour presently serve as Directors of the Corporation. Mr. Ansour was initially recommended to serve as a Director by Dr. Vinciarelli.

If elected, each Nominee will serve until the 20212022 Annual Meeting of Stockholders and until his respective successor is duly elected and qualified or until his death, resignation, or removal. Properly executed Proxy Cards will be voted FOR the Nominees unless otherwise specified. Each Nominee has consented to stand for election and the Board anticipates each of the Nominees, if elected, will serve as a Director.

However, if any person nominated by the Board is unable to serve or, for good cause, will not serve, proxies solicited hereby will be voted for the election of another person designated by the Board, if one is nominated.

A plurality of the votes cast for a Nominee by the Stockholders of Common Stock and Class B Common Stock, voting together as a single class, shall elect such Nominee. Accordingly, abstentions, brokernon-votes (if any), and votes withheld from any Nominee will have no effect on this proposal. There is no cumulative voting.

Dr. Vinciarelli beneficially owned, as of March 31, 2020, 9,861,6052021, 10,010,893 shares of Common Stock, 311,954155,977 of which Dr. Vinciarelli has the right to acquire upon exercise of options to purchase Common Stock within 60 days of March 31, 2020,2021 and 11,023,648 shares of Class B Common Stock, together representing 81.5%80.4% of the voting power of the outstanding stock of the Corporation, sufficient to elect each of the Nominees named below. He has stated an intention to vote in favor of fixing the number of Directors at eightnine and in favor of the election of all Nominees.

Information Regarding Nominees and Qualifications

The following sets forth certain information as of March 31, 2020,April 30, 2021, with respect to the eightnine Nominees for election to the Board. The information presented includes information each Director or Nominee has provided us about age, all positions held, principal occupation and business experience for the past five years, and the names of other publicly-held companies for which the Director or Nominee currently serves as a director or has served as a director during the past five years. In addition, the information presented below describes each Nominee’s specific experience, qualifications, and skills that led the Board as a whole to conclude the Nominee possessed the necessary attributes to serve as a Director. In addition to the experience, qualifications, and skills of each Director,Nominee, the Board as a whole also considers each Nominee’s reputation for integrity, honesty, and adherence to high ethical standards.

Information regarding the beneficial ownership of shares of the capital stock of the Corporation by such persons is set forth in the section of this Proxy Statement entitled “Principal and Management Stockholders.” See also “Certain Relationships and Related Party Transactions.” There is no family relationship among any of the Directors, Nominees and/or executive officers of the Corporation.

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The Corporation previously announced the appointment of James F. Schmidt as Corporate Vice President, Chief Financial Officer, Treasurer, and Corporate Secretary, effective June 1, 2021. The Board intends to increase the size of the Board to ten Directors and appoint Mr. Schmidt to the Board for a one year term following the Annual Meeting.

The Board unanimously recommends a vote FOR fixing the number of Directors at eightnine and the election of all of the Nominees.

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CORPORATE GOVERNANCE

Status as a Controlled Company

As of March 31, 2020,2021, there were 28,903,41931,762,312 shares of Common Stock and 11,758,218 shares of Class B Common Stock of the Corporation outstanding and entitled to vote. Our Common Stock is listed for trading on the NASDAQ Global Select Market(“NASDAQ-GS”) and, as such, we are subject to the listing requirements set forth in the Marketplace Rules of the NASDAQ Stock Market LLC (the “Nasdaq Rules”). The Corporation is a “controlled company” in accordance with the governance provisions of the Nasdaq Rules, because Dr. Vinciarelli, Chairman of the Board, President, and Chief Executive Officer, holds more than 50% of the voting power of our outstanding capital stock. Accordingly, the Corporation relies on certain exemptions from corporate governance requirements available to us under the Nasdaq Rules for a controlled company (Nasdaq Rule 5615(c)(2)).

Dr. Vinciarelli beneficially owned, as of March 31, 2020, 9,861,6052021, 10,010,893 shares of our Common Stock, 311,954155,977 of which Dr. Vinciarelli has the right to acquire upon exercise of options to purchase Common Stock within 60 days of March 31, 2020,2021, and 11,023,648 shares of our Class B Common Stock. Each share of Class B Common Stock entitles the holder thereof to 10 votes per share and is exchangeable on a one for one basis into a share of Common Stock, which entitles the holder thereof to one vote per share. As of March 31, 2020,2021, Dr. Vinciarelli beneficially owned 33.7%31.4% of our Common Stock and 93.8% of our Class B Common Stock, which together represent 81.5%80.4% of total voting power, giving him effective control of our governance.

Because of the Corporation’s status as a controlled company, we are not required to comply with listing standards requiring a majority of independent Directors on our Board, the determination of the compensation of our executive officers solely by independent Directors, and the recommendation of nominees for Director solely by independent Directors. Upon consideration of the independence criteria under the Nasdaq Rules, the Board has determined that threefour of the eightnine Nominees (Mr.(three of which are current Directors: Mr. Anderson, Mr. Carlson, and Dr. Eichten), who are also Directors,Eichten and one of which is not yet a Director: M. Michael Ansour) are independent, as defined by the Nasdaq Rules. In addition, the Board previously determined that Liam K. Griffin, who served as a Director and a member of the Audit and Compensation Committees in 2019 (until the 2019 Annual Meeting of Stockholders at which Mr. Griffin did not stand forre-election), was independent under applicable SEC and Nasdaq Rules, including SEC and Nasdaq Rules applicable to audit committee and compensation committee members.

While we do rely on an exemption, as a controlled company, from the Nasdaq Rules requirement that our Board be comprised of a majority of independent Directors, the Nasdaq Rules nevertheless require our Board to have an Audit Committee comprised of no fewer than three Directors, all of whom are independent. The Nasdaq Rules further require that all members of the Audit Committee have the ability to read and understand fundamental financial statements and that at least one member of the Audit Committee possess financial sophistication (i.e., qualify to be identified as an “audit committee financial expert” under Item 407(d)(5)(ii) and (iii) of RegulationS-K). Mr. Anderson, Mr. Carlson, and Dr. Eichten are standing forre-election to the Board and, ifre-elected, intend to serve as members of the Audit Committee for theupcoming one-year term. The Board has determined each of these Directors is independent under the Nasdaq Rules, including the Nasdaq Rules applicable to audit committee members. The Board also has determined that Mr. Carlson qualifies as an “audit committee financial expert” under Item 407(d)(5)(ii) and (iii) of RegulationS-K.

We rely on an exemption, as a controlled company, from the Nasdaq Rules requirement that the compensation of our executive officers, including Dr. Vinciarelli, our Chief Executive Officer, be determined solely by independent Directors. However, Mr. Anderson, Mr. Carlson, and Dr. Eichten, all considered to be independent Directors under the Nasdaq Rules, including the Nasdaq Rules applicable to compensation committee members, are standing forre-election to the Board and, ifre-elected, intend to serve as members of the Compensation Committee for theupcoming one-year term. The Compensation Committee is solely responsible for the administration of the Corporation’s stock option plans, with authority delegated by the Board to approve all recommended stock option awards.

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independent Directors). The Board believes it, as a whole, is in the best position to evaluate potential candidates for nomination as Director and, therefore, the full Board (including Directors who are not independent) performs the function of such a committee. Of the current Directors, Dr. Vinciarelli, Mr. Tuozzolo, Mr. Simms,McNamara, Mr. McNamara,Davies and Mr. DaviesD’Amico are not independent Directors under applicable Nasdaq Rules. In addition, H. Allen HendersonMr. Simms, who is also a Director and Barry Kelleher, who served as Directorsa Director in 2019, but did2020, is not standstanding forre-election at the 2019 Annual Meeting of Stockholders, wereMeeting. Mr. Simms is not an independent DirectorsDirector under applicable Nasdaq Rules.

Finally, while we rely on the exemptions from certain Nasdaq Rules requirements described above, we are not exempt from the requirement that independent Directors have regularly scheduled meetings at which only independent Directors are present. At each meeting of the Board, the independent Directors conduct such “executive sessions,” frequently with our outside counsel as an invited guest. In addition, at each meeting of the Audit Committee, which is comprised solely of the current three independent Directors, the independent Directors conduct private meetings with representatives of our independent registered public accounting firm, KPMG LLP (“KPMG”).

The Board and Its Committees

The Board held no in-person meetings but acted by written consent in lieu of meetings on seven occasions during 2020. Our Board has two standing committees: the Audit Committee and the Compensation Committee.

The Board heldthree in-person meetings and acted by written consent in lieu of meetings on four other occasions during 2019. Each of the Directors attended 75% or more of the total number of meetings of the Board and meetings of the committees thereof on which such Director serves. Directors are expected to attend each year’s Annual Meeting in person unless doing so is impracticable due to unavoidable conflicts. All of the Directors attended the 2019 Annual Meeting of Stockholders.

Information regarding the functions performed by the Audit Committee is set forth in the section of this Proxy Statement entitled “Report of the Audit Committee.” The Audit Committee is governed by a written charter, approved by the Board on February 3, 2007, and reviewed each year. As stated above, the Board has determined that Mr. Anderson, Mr. Carlson, and Dr. Eichten are independent, and that Mr. Carlson meets the definition of “audit committee financial expert” as defined by Item 407(d) ofRegulation S-K. Mr. Anderson, Mr. Carlson, and Dr. Eichten have agreed, ifre-elected, to serve on the Audit Committee. The charter of the Audit Committee is posted on the Corporation’s website, www.vicorpower.com, under the heading “About Vicor”the Company” and the subheading “Corporate Governance.” The Audit Committee held five meetings during 2019.2020.

The Compensation Committee is responsible for approving, based on the recommendation of Dr. Vinciarelli, the compensation for the executive officers of the Corporation, approving all grants of stock options by the Corporation and its subsidiaries, and administering the Corporation’s stock option plans pursuant to authority delegated to it by the Board. The Compensation Committee is governed by a written charter, approved by the Board on October 18, 2013, and subject to review each year. The Compensation Committee held five meetings during 20192020 and acted by written consent in lieu of meeting on 1715 other occasions to approve stock option awards granted during 2019.2020. The Compensation Committee charter is posted on the Corporation’s website, www.vicorpower.com, under the heading “About Vicor”the Company” and the subheading “Corporate Governance.”

Each of the Directors attended 75% or more of the total number of meetings of the Board and meetings of the committees thereof on which such Director serves. Directors are expected to attend each year’s Annual Meeting in person unless doing so is impracticable due to unavoidable conflicts. All of the Directors attended the 2020 Annual Meeting of Stockholders.

Board Leadership and Role in Risk Management

Given the Corporation’s status as a controlled company and Dr. Vinciarelli’s leadership of the Corporation since its founding, he fulfills both the roles of Chairman of the Board and Chief Executive Officer. As Chairman of the Board, Dr. Vinciarelli presides over meetings of the Board and, in collaboration with Mr. Simms, in his capacity asthe Corporate Secretary, establishes an agenda for each meeting. The Board does not have a lead independent Director. As Chief Executive Officer, Dr. Vinciarelli is responsible for setting the strategic direction of the Corporation, the leadership of the organization, and the operational and financial performance of the Corporation.

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The Board advises and oversees executive management, which, under Dr. Vinciarelli’s leadership, is responsible for theday-to-day operations of the Corporation’s affairs. The Board reviews, assesses, and directs our long-term strategic plans and provides oversight and guidance on all matters influencing the Corporation’s well-being.

The Board has an active role, as a whole and also at the committee level, in overseeing identification, analysis, and management of the Corporation’s risks. The Board regularly reviews information regarding the Corporation’s strategy, operations, financial performance and position, and legal and regulatory affairs, addressing the risks associated with each. To date, Messrs. Davies, McNamara, Simms, and Tuozzolo, in their capacities as Corporate Vice President, Global Sales and Marketing, Corporate Vice President, General Manager, Operations, former Chief Financial Officer, and former President of Picor Corporation (“Picor”),Vicor Power Components, respectively, provide first-hand information and insight to the Board regarding enterprise risk. Messrs. Anderson and Carlson, as semiconductor industry executives with extensive, valuable experience, provide important external perspectives on a range of challenges facing the Corporation, including evolving technology and intensifying competition. Dr. Eitchen, an early investor in the Corporation, who has served on the Board for 3940 years, provides important perspectives on technology trends, as well as a historical perspective on corporate strategy. Mr. D’Amico provides input on patent matters, including risk related to potential patent litigation, given his considerable experience in the field of patent law, including patent litigation, patent licensing and patent prosecution. The independent Directors, given their breadth of experience and expertise, as well as their governance responsibilities as the sole members of the Audit Committee and the Compensation Committee, contribute to an ongoing assessment of the integrity of our financial reporting processes and systems and the appropriateness and effectiveness of our compensation programs.

While the Board is ultimately responsible for the Corporation’s risk management, the Audit Committee, comprised of independent Directors, plays a primary and important role in assisting the Board in overseeing such responsibilities, with particular focus, as mandated by the Sarbanes-Oxley Act of 2002, on the integrity and effectiveness of the Corporation’s financial reporting processes. The Audit Committee reviews our guidelines and policies on management of enterprise risks, including assessment and management of the Corporation’s major financial exposures and management’s monitoring and control of such exposures. At each meeting of the Audit Committee, members of management, led by Mr. Simms, in his capacity asthe Corporation’s Chief Financial Officer, present information addressing issues related to risk identification, analysis, and mitigation. Also at each meeting of the Audit Committee, the committee members meet privately with representatives of our independent auditors, KPMG.

In addition to the risk oversight role undertaken by the Audit Committee, the Compensation Committee assists the Board in overseeing the Corporation’s compensation policies and practices as they relate to the Corporation’s risk management and risk-taking incentives. The Compensation Committee has determined that the compensation policies and practices for the Corporation’s employees are not reasonably likely to have a material adverse effect on the Corporation, as the incentives of the Corporation’s compensation programs are believed to be aligned with our strategic, operational, and financial goals and the interest of our Stockholders.

Director Nomination Process

As indicated above, the full Board performs the Director nomination function for the Corporation. The Board does not have a charter governing the Director nomination process, although it has established Director nomination procedures setting forth the process for identifying and evaluating Director nominees. The Corporation’sBy-Laws require that our Stockholders approve the number of Directors for the coming year at each Annual Meeting of Stockholders, although theBy-Laws also allow the Board to reduce the number of Directors in the event of a vacancy on the Board and to increase the number of Directors at any time by majority vote of the Directors then serving.

In connection with the appointment, effective June 1, 2021, of James F. Schmidt as Corporate Vice President, Chief Financial Officer, Treasurer, and Corporate Secretary, following the Annual Meeting, the Board

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intends to increase the size of the Board to ten Directors and appoint Mr. Schmidt to the Board for a one year term.

Board Membership Criteria— At a minimum, the Board must be satisfied each candidate for nomination has high personal and professional integrity, has demonstrated exceptional ability and judgment, and is expected, in the judgment of the Board, to be highly effective, in collaboration with the other nominees to the Board, in

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Any stockholder seeking to present a Director nomination at an annual meeting must comply with the notice procedures in ourBy-Laws as described herein under “Stockholder Proposals.”

Communications with the Board

If a Stockholder wishes to communicate with any Director or the Board as a whole, he or she may do so by addressing such communications to: [Name(s) of Director(s)/Board of Directors of Vicor Corporation], c/o James

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Picor Corporation (“Picor”) and VI Chip subsidiaries of the Corporation. From 2011 to 2014, he served as Vice President of Marketing and Business Development for Picor. Prior to joining Picor, Mr. Gendron held senior marketing and sales roles at various semiconductor companies including Analog Devices, STMicroelectronics, Fairchild Semiconductor, International Rectifier, and Volterra. Mr. Gendron also serves on the Industrial Advisory Board for the University of New Hampshire Department of Electrical and Computer Engineering. He holds a B.S. in Electrical Engineering from Clarkson University, a M.S. in Electrical Engineering from Northeastern University, and a M.B.A. from the Whittemore School of Business at the University of New Hampshire, and is a registered Professional Engineer by the Commonwealth of Massachusetts.

Nancy L. Grava,49,50, Corporate Vice President, Human Resources, since July 2015. From 2009 to June 2015, Ms. Grava held the position of Director, Human Resources. From 2002 to 2009, Ms. Grava held the position of Senior Manager, Compensation and Benefits and, from 1999 to 2002, she held the position of Manager, Compensation and Benefits. Prior to that time, Ms. Grava held various other positions within Human Resources since joining the Corporation in 1993. Ms. Grava received a B.A. from the Massachusetts School of Liberal Arts and an M.B.A. from Bentley University.

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Secretary from 2008 through his resignation on April 16, 2021. In 2016, Mr. Simms was appointed President and Chief Executive Officer of VLT, Inc., a wholly-owned subsidiary of the Corporation that owned a majority of the Corporation’s patents. VLT, Inc. was subsequently merged with and into the Corporation in August 2020. From 2007 until 2008, he was a Managing Director of Needham & Company, LLC, an investment banking and asset management firm. Previously, he had served as a Managing Director with the investment banking firm of Janney Montgomery Scott LLC, from 2004 to 2007 and as a Managing Director of the investment banking firm of Adams, Harkness & Hill, Inc. from 1997 to 2004. Mr. Simms served as a member of the Board of Directors of PAR Technology Corporation from 2001 to 2014. Mr. Simms received a B.A. from the University of Virginia and an M.B.A. from the University of Pennsylvania’s Wharton School. Mr. Simms has served on the Company’s Board of Directors since 2008. Mr. Simms is not standing for re-election to the Board of Directors at the Annual Meeting.

PRINCIPAL AND MANAGEMENT STOCKHOLDERS

The following table sets forth the beneficial ownership of the Corporation’s Common Stock and Class B Common Stock held by (1) each person or entity known to the Corporation to be the beneficial owner of more than five percent of the outstanding shares of either class of the Corporation’s common stock, (2) each Director and Nominee, (3) each named executive officer of the Corporation (as defined in Item 402(a)(3) of RegulationS-K)S-K and named in the Summary Compensation Table for Fiscal 2020 below), and (4) all Directors, Nominees and executive officers as a group, in each case based on representations of the Directors, Nominees and executive officers as of March 31, 2020,2021, and a review of filings on Schedules 13D and 13G under the Exchange Act. Except as otherwise specified, the named beneficial owner has sole voting and investment power over the shares set forth opposite such beneficial owner’s name. The information in the table reflects shares outstanding of each of the two classes of common stock on March 31, 2020,2021, and does not, except as otherwise indicated below, take into account conversions after such date, if any, of shares of Class B Common Stock into Common Stock, which, if they were to occur, would increase the voting control of persons who retain shares of Class B Common Stock.

The percentages shown have been determined as of March 31, 2020,2021, in accordance with Rule13d-3 under the Exchange Act, and are based on a total of 40,661,63743,520,530 shares of common stock that were outstanding on such

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Pursuant to the provisions of our certificate of incorporation, shares of Class B Common Stock are transferrable only under the limited circumstances set forth therein and must be converted into shares of Common Stock in order to be sold. Such conversion may be effected by the delivery of the certificate(s) representing shares of Class B Common Stock, accompanied by a written notice of the election by the record holder thereof to convert, to either Mr. Simms, in his capacity asthe Corporate Secretary, c/o Vicor Corporation, 25 Frontage Road, Andover, MA 01810, or to the then-current transfer agent for our Common Stock. Any transfer of shares of Class B Common Stock not permitted under the provisions of our certificate of incorporation will result in the automatic conversion of those shares of Class B Common Stock into an equal number of shares of Common Stock.

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COMPENSATION DISCUSSION AND ANALYSIS

This section provides information about our overall compensation program elements and objectives, with a particular focus on the compensation decisions made during 2020 with respect to our “Named Executive Officers” (as defined in Item 402(a)(3) of Regulation S-K), which were the following individuals for 2020: Dr. Vinciarelli, our President and Chief Executive Officer; Mr. Simms, who served as our Chief Financial Officer until his resignation on April 16, 2021; and Messrs. Davies, McNamara and Tuozzolo, each of whom is a Vice President of the Corporation.

Philosophy

The primary objective of the Corporation’s compensation programs is to attract, motivate, and retain highly qualified and productive employees using a combination of cash and equity based rewards intended to motivate and reward superior performance. Salaries and, in appropriate circumstances, cash bonuses encourage effective performance relative to current plans and objectives, while stock options may be utilized to attract new employees, reward outstanding performers, promote longer-term focus, and more closely align the interests of employees with those of Stockholders.

Stockholder Advisory Vote on Executive Compensation

At the 2017 annual meeting of Stockholders, Stockholders cast an advisory vote on the frequency of future advisory votes on the compensation of our Named Executive Officers (“Say on Pay” votes). The option receiving the highest number of votes was a frequency of every three years, and, in accordance with the outcome of that advisory vote, our Board determined to hold a Say on Pay advisory vote every three years. The Corporation’s most recent Say on Pay vote occurred at the Corporation’s 20172020 annual meeting of Stockholders, and Stockholders approved, on an advisory basis, the compensation of our Named Executive Officers as disclosed in our proxy statement for that annual meeting. The Compensation Committee believes this affirmed our Stockholders’ support of the Corporation’s approach to executive compensation and, therefore, did not change its approach during 2018 or 2019. As described in Proposal Two of this Proxy Statement, at the Annual Meeting, Stockholders will have the opportunity to vote, on an advisory basis, on the compensation of our Named Executive Officers.2020. The next advisory vote on the frequency of future Say on Pay votes will occur at the 2023 annual meeting of Stockholders.

Overview of Executive Compensation

Dr. Vinciarelli, with input from Ms. Grava, our Corporate Vice President, Human Resources, makes periodic recommendations to the Compensation Committee with respect to the compensation of executives including the Named Executive Officers (other than himself) and other employees in leadership positions. The Compensation Committee approves the annual salary of Dr. Vinciarelli and the other Named Executive Officers (as defined in Item 402(a)(3) of RegulationS-K) of the Corporation. Our Named Executive Officers for 2019 were Dr. Vinciarelli and Messrs. Simms, Davies, Gendron and Tuozzolo.

Potential elements of compensation for our executive officers include: a base salary, cash bonuses, stock option awards through the Corporation’s stock option plans, the option to purchase Common Stock of the Corporation through the 2017 Employee Stock Purchase Plan (“ESPP”), subsidized participation in group health, disability, and life insurance, cash contributions to a 401(k)tax-qualified retirement saving plan sponsored by the Corporation and certain perquisites. All employees, including our Named Executive Officers, areemployees-at-will and, as such, do not have employment contracts with the Corporation.

Each component of compensation is described in the following table:

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Stock Option ProgramsAwards

Discretionary awards of stock options for the purchase of shares of Vicor Corporation, as well as VI Chip (prior to the VI Chip Merger in June 2019), have been a component of our compensation for executives and employees considered bythat Dr. Vinciarelli considers to be important contributors to the Corporation’s success. The Compensation Committee approves all stock option grants. We generally award a limited number ofnon-qualified stock options to a new employee upon hiring. Prior to the VI Chip Merger in June 2019, depending upon the business unit into which an individual was hired, we awarded stock options for the purchase of shares of Vicor Corporation and/or VI Chip. Certain new hires have been awarded stock options granted by both entities. From time to time, existing employees willmay also be rewarded for superior performance through the award of additional stock options.

The Corporation does not have a policy regarding the composition or frequency of discretionary awards of stock options or other forms of equity-based compensation. Mr. Davies and Mr. Gendron each received a discretionary award of stock options in 2019.In 2020, Mr. Simms, Mr. Davies, Mr. McNamara and Mr. Tuozzolo each received an award of stock options due to their service on the Board, as described below under the section entitled “Directors’ Compensation For Fiscal 2019.2020.” In addition, Mr. Davies, Mr. McNamara and Mr. Tuozzolo each received an award of stock options in lieu of an annual compensation increase.

During 2020, as was also the case in 2019 2018, and 2017,2018, options for the purchase of the Corporation’s Common Stock were awarded under the Vicor Corporation Amended and Restated 2000 Stock Option and Incentive Plan, as amended and restated (the “Vicor 2000 Plan”). The exercise price of stock options for the purchase of the Corporation’s Common Stock is set at the closing price of a share of the Corporation’s Common Stock on theNASDAQ-GS on the effective date of the grant. Generally, these option grants vest evenly each quarter over five years and have a10-year term. In certain circumstances, options have been awarded with vesting provisions based on the achievement of specific financial performance targets, as defined in the award agreement associated with those options.

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Prior to the VI Chip Merger in June 2019, options for the purchase of VI Chip common stock were awarded under the VI Chip Corporation Amended and Restated 2007 Stock Option and Incentive Plan (the “2007 VI Chip Plan”). In connection with the VI Chip Merger, the Corporation assumed the 2007 VI Chip Plan and any outstanding stock options thereunder. All outstanding options under the 2007 VI Chip Plan have been converted into options for the purchase of Common Stock of the Corporation, as discussed in more detail below under “—Conversion ofCorporation. The 2007 VI Chip Options UponPlan, which was previously approved by the Corporation’s stockholders at the 2017 Annual Meeting of Stockholders, was amended and restated on June 28, 2019 in connection with the VI Chip Merger. The assumed 2007 VI Chip Plan, as amended and restated, is referred to herein as the “Assumed VI Chip Plan.”

Prior to 2018, options for the purchase of Picor common stock were awarded under the Amended and Restated Picor Corporation 2001 Stock Option and Incentive Plan (the “2001 Picor Plan”). In connection with the merger of Picor with and into the Corporation in May 2018 (the “Picor Merger”), the Corporation assumed the 2001 Picor Plan, as well as any outstanding stock option awards under the 2001 Picor Plan. All outstanding options under the 2001 Picor Plan were converted into options for the purchase of Common Stock of the Corporation. The 2001 Picor Plan, which was previously approved by the Corporation’s stockholders at the 2017 Annual Meeting of Stockholders, was amended and restated on May 30, 2018 in connection with the Picor Merger. The assumed 2001 Picor Plan, as amended and restated, is referred to herein as the “Assumed Picor Plan.”

Conversion of VI Chip Options Upon VI Chip Merger

On June 28, 2019, VI Chip, which previously was 99.9% owned by the Corporation, was merged with and into the Corporation (which is referred to herein as the “VI Chip Merger”). In connection with the closing of the VI Chip Merger, the Corporation assumed the 2007 VI Chip Plan, as well as any outstanding stock option awards, whether vested or unvested, under the 2007 VI Chip Plan (the “Plan Assumption”). Each outstanding option to acquire a share of the common stock of VI Chip, was converted into an option to purchase a number of shares of the Corporation’s Common Stock with an adjusted exercise price, with the adjusted number of shares and option exercise price determined based on an exchange ratio of one share of VI Chip common stock for 0.1418 shares of Common Stock of the Corporation.

The 2007 VI Chip Plan, which was previously approved by the Corporation’s stockholders at the 2017 Annual Meeting of Stockholders, was amended and restated on June 28, 2019 in connection with the VI Chip Merger to (i) provide that option awards granted under the 2007 VI Chip Plan will be settled in shares of the Corporation’s Common Stock, (ii) adjust the number of shares that are issuable under the assumed 2007 VI Chip Plan pursuant to the exchange ratio described above, and (iii) provide that no new awards may be granted under the 2007 VI Chip Plan after the completion of the VI Chip Merger. The assumed 2007 VI Chip Plan, as amended and restated, is referred to herein as the “Assumed VI Chip Plan.”

As a result of the Plan Assumption, 1,476,371 shares of the Corporation’s Common Stock were reserved and made available for issuance under the Assumed VI Chip Plan solely upon the exercise of the assumed options. No additional awards or any other types of awards may be granted under the Assumed VI Chip Plan.

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Stock options issued under the Vicor 2000 Plan, the Assumed Picor Plan, and the Assumed VI Chip Plan carry a change in control provision that automatically accelerates vesting and makes unvested options fully exercisable upon a change of control, as defined in the applicable plan.

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OPTIONS EXERCISES AND STOCK VESTED FOR FISCAL 20192020

The following table presents option exercises by our Named Executive Officers during 2019.2020. All options exercised by Named Executive Officers during 20192020 were under the Vicor Plans as follows:

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Based on this information, the ratio of the annual total compensation of our Chief Executive Officer to the annual total compensation of our median employee is estimated to be 72.3 to 1.

We identified our median employee using a multi-step process. First, we examined the base salaries and wages of all individuals employed by us on December 31, 20192020 (other than Dr. Vinciarelli), whether full-time, part-time, or on a seasonal basis to identify the median base salary of all our employees. We annualized wages and salaries for all permanent employees who were hired after January 1, 2019,2020, as permitted by SEC rules, and converted all employees’ salaries or wages into U.S. dollars based on the applicable foreign exchange rate on December 31, 2019.2020. We selected the individual within such group whose total compensation was at the median to serve as our median employee whose compensation is disclosed above. After we identified our median employee, we calculated such employee’s total annual compensation in the same way that we calculate the annual total compensation of our named executive officers in the Summary Compensation Table.

DIRECTORS’ COMPENSATION FOR FISCAL 20192020

Overview of Director Compensation

The level of compensation ofnon-employee Directors is reviewed on an annual basis by the Board as a whole. To determine the appropriateness of the current level of compensation fornon-employee Directors, the

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