UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

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

Exchange Act of 1934

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 Pursuant to §240.14a-12

Exponent, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(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.

1

Exponent, Inc. Online Go to www.envisionreports.com/EXPO or scan the QR code — login details are located in the shaded bar below. Stockholder Meeting Notice Important Notice Regarding the Availability of Proxy Materials for the Exponent, Inc. Stockholder Meeting to be Held on June 3, 2021 Under Securities and Exchange Commission rules, you are receiving this notice that the proxy materials for the annual stockholders’ meeting are available on the Internet. Follow the instructions below to view the materials and vote online or request a copy. The items to be voted on and location of the annual meeting are on the reverse side. Your vote is important! This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. We encourage you to access and review all of the important information contained in the proxy materials before voting. The Exponent 2020 Annual Report, Exponent 2021 Notice of Annual Stockholders Meeting and Proxy Statement are available at: http://www.envisionreports.com/EXPO Easy Online Access — View your proxy materials and vote. Step 1: Go to www.envisionreports.com/EXPO. Step 2: Click on Cast Your Vote or Request Materials. Step 3: Follow the instructions on the screen to log in. Step 4: Make your selections as instructed on each screen for your delivery preferences. Step 5: Vote your shares. When you go online, you can also help the environment by consenting to receive electronic delivery of future materials Obtaining a Copy of the Proxy Materials – If you want to receive a copy of the proxy materials, you must request one. There is no charge to you for requesting a copy. Please make your request as instructed on the reverse side on or before May 24, 2021 to facilitate timely delivery. 2NOT

ckholder Meeting Notice The 2021 Annual Meeting of Stockholders of Exponent, Inc. will be held on June 3, 2021 at 8:00 a.m. PDT, virtually via the internet at www.meetingcenter.io/289121296. To access the virtual meeting, you must have the information that is printed in the shaded bar located on the reverse side of this form. The password for this meeting is EXPO2021. Proposals to be voted on at the meeting are listed below along with the Board of Directors’ recommendations. The Board of Directors recommend a vote FOR all the nominees listed and FOR Proposals 2-3: 1. Election of Directors: 01 George H. Brown 02 Catherine Ford Corrigan, Ph.D 03 Paul R. Johnston, Ph.D. 04 Carol Lindstrom 05 Karen A. Richardson 06 John B. Shoven, Ph.D. 07 Debra L. Zumwalt 2. To ratify the appointment of KPMG LLP, as independent registered public accounting firm for the Company for the fiscal year ending December 30, 2022. 3. To approve, on an advisory basis, the Fiscal 2021 compensation of the Company’s named executive officers. PLEASE NOTE – YOU CANNOT VOTE BY RETURNING THIS NOTICE. To vote your shares you must go online or request a paper copy of the proxy materials to receive a proxy card. If you wish to attend and vote at the meeting, please bring this notice with you. Here’s how to order a copy of the proxy materials and select delivery preferences: Current and future delivery requests can be submitted using the options below. If you request an email copy, you will receive an email with a link to the current meeting materials. PLEASE NOTE: You must use the number in the shaded bar on the reverse side when requesting a copy of the proxy materials. Internet – Go to www.envisionreports.com/EXPO. Click Cast Your Vote or Request Materials. Phone – Call us free of charge at 1-866-641-4276. Email – Send an email to investorvote@computershare.com with “Proxy Materials Exponent, Inc.” in the subject line. Include your full name and address, plus the number located in the shaded bar on the reverse side, and state that you want a paper copy of the meeting materials. To facilitate timely delivery, all requests for a paper copy of proxy materials must be received by May 24, 2021.

Exponent, Inc. Your vote matters – here’s how to vote! You may vote online or by phone instead of mailing this card. Online Go to www.envisionreports.com/EXPO or scan the QR code — login details are located in the shaded bar below. Phone Call toll free 1-800-652-VOTE (8683) within the USA, US territories and Canada Save paper, time and money! Sign up for electronic delivery at www.envisionreports.com/EXPO Using a black ink pen, mark your votes with an X as shown in this example. Please do not write outside the designated areas. 2021 Annual Meeting Proxy Card IF VOTING BY MAIL, SIGN, DETACH AND RETURN THE BOTTOM PORTION IN THE ENCLOSED ENVELOPE A Proposals — The Board of Directors recommend a vote FOR all the nominees listed and FOR Proposals 2 – 3 1. Election of Directors: For Against Abstain 01 - George H. Brown 02 - Catherine Ford Corrigan, Ph.D 03 - Paul R. Johnston, Ph.D. 04 - Carol Lindstrom 05 - Karen A. Richardson 06 - John B. Shoven, Ph.D 07 - Debra L. Zumwalt 2. To ratify the appointment of KPMG LLP, as independent registered public accounting firm for the Company for the fiscal year ending December 30, 2022. For Against Abstain 3. To approve, on an advisory basis, the Fiscal 2021 compensation of the Company’s named executive officers. For Against Abstain B Authorized Signatures — This section must be completed for your vote to count. Please date and sign below Please sign exactly as name(s) appears hereon. Joint owners should each sign. When signing as attorney, executor, administrator, corporate officer, trustee, guardian, or custodian, please givtitle. Date (mm/dd/yyyy) — Please print date below. Signature 1 — Please keep signature within the box. Signature 2 — Please keep signature within the box 72BM

The 2021 Annual Meeting of Stockholders of Exponent, Inc. will be held on June 3, 2021 at 8:00 a.m. PDT, virtually via the internet at www.meetingcenter.io/289121296. To access the virtual meeting, you must have the information that is printed in the shaded bar located on the reverse side of this form. The password for this meeting is — EXPO2021. Small steps make an impact. Help the environment by consenting to receive electronic delivery, sign up at www.envisionreports.com/EXPO IF VOTING BY MAIL, SIGN, DETACH AND RETURN THE BOTTOM PORTION IN THE ENCLOSED ENVELOPE. Notice of 2021 Annual Meeting of Stockholders Proxy Solicited by Board of Directors for Annual Meeting — June 3, 2021 Catherine Ford Corrigan and Richard L. Schlenker, or any of them, each with the power of substitution, are hereby authorized to represent and vote the shares of the undersigned, with all the powers which the undersigned would possess if personally present, at the Annual Meeting of Stockholders of Exponent, Inc. to be held on June 3, 2021 or at any postponement or adjournment thereof. Shares represented by this proxy will be voted by the stockholder. If no such directions are indicated, the Proxies will have authority to vote FOR the election of the Board of Directors and FOR items 2-3. In their discretion, the Proxies are authorized to vote upon such other business as may properly come before the meeting. (Items to be voted appear on reverse side) C Non-Voting Items Change of Address — Please print new address below Comments — Please print your comments