InterDigital, Inc.

Adjusted EBITDA is a supplementalnon-GAAP financial measure that InterDigital believes provide investors with important insight into the company’s ongoing business performance. InterDigital defines Adjusted EBITDA as net income attributable to InterDigital Inc. plus net loss attributable tonon-controlling interest, income tax (provision) benefit, other income (expense) & interest expense, depreciation and amortization, share-based compensation, and other items. Other items include restructuring costs, impairment charges and othernon-recurring items. Thisnon-GAAP financial measure may be calculated differently from, and therefore may not be comparable to, similarly titled measures used by other companies. A detailed reconciliation of Adjusted EBITDA to the most directly comparable GAAP financial measure is provided below.

Pro Forma EBITDA is a supplementalnon-GAAP financial measure that InterDigital uses for compensation purposes as described in this proxy statement. InterDigital defines Pro Forma EBITDA as total revenues minus operating expenses plus depreciation and amortization, intellectual property enforcement costs, and other items. Other items include restructuring costs, impairment charges and othernon-recurring items, as further described below. Thisnon-GAAP financial measure may be calculated differently from, and therefore may not be comparable to, similarly titled measures used by other companies. A detailed reconciliation of Pro Forma EBITDA to the most directly comparable GAAP financial measure is provided below.

INTERDIGITAL, INC. 200 BELLEVUE PARKWAY, SUITE 300 WILMINGTON, DE 19809-3727 VOTE BY INTERNET Before The Meeting—Go to www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information. Vote by 11:59 P.M. Eastern Time on June 4, 2024 for shares held directly and by 11:59 P.M. Eastern Time on May 30, 2024 for shares held in a Plan. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. During The Meeting—Go to www.virtualshareholdermeeting.com/IDCC2024 You may attend the Meeting via the Internet and vote during the Meeting. Have the information that is printed in the box marked by the arrow available and follow the instructions. VOTE BYPHONE—1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions. Vote by 11:59 P.M. Eastern Time on June 4, 2024 for shares held directly and by 11:59 P.M. Eastern Time on May 30, 2024 for shares held in a Plan. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717. TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: E69637-P22916 KEEP THIS PORTION FOR YOUR RECORDS — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED.

The Board of Directors recommends you vote FOR the election of each of the following nominees: Nominees: For Against Abstain The Board of Directors recommends you vote FOR For Against Abstain proposal 2: 2. Advisory resolution to approve executive compensation. The Board of Directors recommends you vote FOR For Against Abstain proposal 3: Lawrence (Liren) Chen 3. Ratification of PricewaterhouseCoopers LLP as the independent registered public accounting firm of InterDigital, Inc. for the year ending December 31, 2024. John A. Kritzmacher Pierre-Yves Lesaicherre ANNUAL REPORT. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date

INTERDIGITAL, INC. 2024 Annual Meeting of Shareholders June 5, 2024 2:00 P.M. Eastern Time Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice of Meeting, Proxy Statement and 2023 Annual Report are available at www.proxyvote.com. — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — E69638-P22916 INTERDIGITAL, INC. 2024 Annual Meeting of Shareholders To Be Held June 5, 2024 THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS The undersigned shareholder of InterDigital, Inc., a Pennsylvania corporation, revoking all previous proxies, hereby appoints Richard J. Brezski and Joshua D. Schmidt, and each of them acting individually, with full power of substitution, as the proxies of the undersigned to vote, as indicated on the reverse side of this proxy card and in their discretion upon such other matters as may properly come before the meeting and any adjournment or postponement thereof, and to vote in accordance with the recommendations of the Board of Directors on all matters as to which a choice is not specified by the undersigned shareholder, all shares that the undersigned would be entitled to vote at the Annual Meeting of Shareholders of InterDigital, Inc. to be held on Wednesday, June 5, 2024, at 2:00 P.M. Eastern Time via the Internet at www.virtualshareholdermeeting.com/IDCC2024, and at any adjournment or postponement thereof. Record holders who attend the virtual annual meeting may vote via the Internet during the meeting; such vote will supersede this proxy. This proxy, when properly executed, will be voted in the manner directed herein. If no such direction is made, this proxy will be voted in accordance with the Board of Directors’ recommendations. Continued and to be signed on reverse side