This Summary, together with the following section entitled “Questions and Answers,” highlights selected information from this proxy statement and does not contain all of the information that may be important to you. You should read carefully the entire proxy statement and the additional documents referred to in this proxy statement for a more complete understanding of the matters being considered at the special meeting. This summary includes references to other parts of this proxy statement to direct you to a more complete description of the topics presented in this summary. This proxy statement is dated [•], 2024 and is first being sent to stockholders of record on or about [•], 2024.

In this proxy statement, the terms “AdTheorent,” the “Company,” “we,” “us” and “our” refer to AdTheorent Holding Company, Inc. and, where appropriate, its subsidiaries. We refer to Cadent, LLC as “Cadent” or “Parent,” Award Merger Sub, Inc. as “Merger Sub,” Novacap Cadent Acquisition Company, Inc. as “Borrower” and Novacap Cadent Holdings, Inc. as “Holdings.” All references to the “merger” refer to the merger of Merger Sub with and into AdTheorent, with AdTheorent continuing as the surviving corporation and becoming a wholly-owned subsidiary of Parent, and all references to the “merger agreement” refer to the Agreement and Plan of Merger, dated as of April 1, 2024, as it may be amended from time to time, by and among AdTheorent, Parent, Merger Sub, Borrower and Holdings, a copy of which is included as Annex A to this proxy statement. AdTheorent, following the consummation of the merger, is sometimes referred to as the “surviving corporation.”

Founded in 2012, we are a digital media platform which focuses on performance-first, privacy-forward methods to execute programmatic digital advertising campaigns, serving both advertising agency and brand customers. Without relying on individualized profiles or sensitive personal data for targeting, we utilize machine learning and advanced data analytics to make programmatic digital advertising more effective and efficient at scale, delivering measurable real-world value for advertisers. Our differentiated advertising capabilities and superior campaign performance, measured by customer-defined business metrics or key performance indicators (“KPIs”), have helped fuel our customer adoption and year-after-year growth.

We use machine learning (“ML”), a subset of artificial intelligence, and advanced data science to organize, analyze and operationalize non-sensitive data to deliver real-world value for customers. Central to our ad-targeting and campaign optimization methods, we build custom machine learning models for each campaign using historic and real-time data to predict future consumer conversion actions for every digital ad impression. We have integrations with Digital Ad Exchanges, or Supply Side Platforms (“SSPs”), from which we are sent ad impression opportunities for evaluation and purchase. We predictively score all ad impression opportunities for the purpose of deciding which ad impressions will likely drive valuable conversions or engagement activity for our customers. Our predictive platform scores up to one million digital ad impressions per second and 75 billion to 85 billion digital ad impressions per day, assigning a predictive score to each. Each predictive score is determined by correlating non-individualized data attributes associated with the particular impression with data corresponding to previously purchased impressions that yielded consumer conversion or engagement activity. Such non-individualized attributes include variables such as publisher, content and URL keywords, device make, device operating system and other device attributes, ad position, geographic data, weather, demographic signals, creative type and size, etc. The “predictive scores” generated by our platform allow us and our advertising clients to determine which ad impressions are more likely or less likely to result in client-desired KPIs. Our machine learning models are customized for every campaign and our platform “learns” over the course of each campaign as it processes more data related to post media view conversion experience. Based on these statistical probabilities or “predictive scores,” our platform automatically determines bidding optimizations to drive conversions and advertiser return on investment (“ROI”) or return on advertising spend (“ROAS”), delivering on approximately 0.001 of the evaluated advertising requests. Our use of machine learning and data science helps us to maximize efficiency and performance, enabling our customers to avoid wasted ad spend related to suboptimal impressions such as impressions that are predicted to be at a greater risk for fraud/invalid traffic or impressions with a higher likelihood of being unviewable, unmeasurable, or not brand safe, among other factors.

Our capabilities extend across the digital ecosystem to identify and engage digital impressions with the highest likelihood of completing customer-desired actions, including online sales, other online actions, and real-world actions such as physical location visitation, in-store sales or vertical specific KPI’s such as prescription fills/lift or submitted credit card applications. Our custom and highly impactful campaign executions encompass popular digital

screens — mobile, desktop, tablet, connected TV (“CTV”), Digital Out of Home (“DOOH”) — and all digital ad formats, including display, rich media, video, native and streaming audio. We actively manage our digital supply to provide advertisers with scale and reach, while minimizing redundant inventory, waste and other inefficiencies. Our CTV capability delivers scale and reach supplemented by innovative and industry recognized machine-learning optimizations towards real-world actions and value-added measurement services.

Our platform and machine learning-based targeting provide privacy advantages that are lacking from alternatives which rely on individual user profiles or cookies employing a “one-to-one” approach to digital ad targeting. Our core targeting approach is statistical, not individualized, and as a result we do not need to compile or maintain user profiles, and we do not rely on cookies or user profiles for targeting. Our solution-set is especially valuable to regulated customers, such as financial institutions and pharmaceutical or health companies, and other privacy-forward advertisers who desire efficient and effective digital ad-targeting without individualized or personal targeting data. We adhere to data usage protocols and model governance processes which help to ensure that each customer’s data is safeguarded and used only for that customer’s benefit, and we take a consultative and collaborative approach to data use best practices with all of our customers.

Supplementing our core machine learning-powered platform capabilities, we offer customized vertical solutions to address the needs of advertisers in specialized industries. These specialized solutions feature vertical-specific capabilities related to targeting, measurement and audience validation. Our broader health offering, which encompasses engagements with customers in the verticals and sub-verticals of healthcare, pharmaceutical, pharmacy, over-the-counter brands, and health-related government (collectively, “AdTheorent Health”), harnesses the power of machine learning to drive superior performance on campaigns targeting both healthcare providers (“HCP”) and patients, employing methods that use individually identifiable health information that has been de-identified in accordance with the Health Insurance Portability and Accountability Act (“HIPAA”) and targeting practices that comply with Network Advertising Initiative (“NAI”) Code of Conduct and other self-regulatory standards. Our AdTheorent Health Predictive Audience Builder (“HABi”) and Health Audiences allows programmatic advertisers to use aggregated health data to research and target “audiences” in a more precise, data-driven and less opaque manner than what is currently available across the industry. This solution leverages primary-sourced, de-identified health data and machine learning to create statistical representations of audiences. These features allow platform users to leverage HABi to build Health Audiences, with the goal of achieving health advertisers’ KPIs, while being privacy forward and HIPAA-compliant by design. In addition, as part of our strategy to establish a scalable foundation for the deployment of innovative verticalized solutions, we launched AdTheorent’s Predictive Audience Builder (“ABi”), a platform tool that allows advertisers to build customizable, machine learning-based predictive audiences for other key verticals. We have also created additional offerings tailored to address the unique challenges and opportunities in a growing range of other verticals.

The Company’s locations are in the United States and Ontario, Canada. The Company’s principal executive offices are located at 330 Hudson Street, 13th Floor, New York, NY 10013, and its telephone number is (800) 804-1359.

AdTheorent is a Delaware corporation and the Company common stock, par value $0.0001 per share (which we refer to as “Company common stock”), trades on The Nasdaq Capital Market^® (which we refer to as “Nasdaq”), under the symbol “ADTH.”

Cadent, LLC, a Delaware limited liability company (which we refer to as “Cadent” or “Parent”) was formed on July 30, 2008. Parent’s principal executive offices are located at 1675 Broadway, 22^nd floor, New York, New York, 10019. Parent’s telephone number is (212) 796-1960.

Award Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Parent (which we refer to as “Merger Sub”), was formed on March 1, 2024, solely for the purpose of engaging in the transactions contemplated by the merger agreement. Upon completion of the merger, Merger Sub will merge with and into AdTheorent and will cease to exist. Merger Sub’s principal executive offices are located at 1675 Broadway, 22^nd floor, New York, New York, 10019. Merger Sub’s telephone number (212) 796-1960.

Parent and Merger Sub are each portfolio companies of Novacap Management Inc. (which we refer to as “Novacap”). Novacap is a leading private equity investment firm focused on the technology, media and communications (TMT), digital infrastructure and financial services sectors with more than $8 billion in assets under management as of December 31, 2023.

In connection with the transactions contemplated by the merger agreement, eight (8) funds (Novacap TMT VI, L.P., Novacap International TMT VI, L.P., Novacap International TMT VI-A, L.P., NVC TMT VI (S.P.), L.P., NVC TMT VI-A (S.P.), L.P., NVC TMT VI, L.P., NVC TMT VI-A, L.P., NVC International TMT VI, L.P.) and an investment vehicle (Novacap TMT VI Co-Investment (Cadent), L.P.) managed by Novacap (which we refer to as the “Novacap Equity Investors”), have provided Parent with an equity commitment, which will be available, together with the debt financing (as described in this proxy statement), as of the closing of the merger, to fund the aggregate merger consideration and to pay the costs, fees, expenses and other amounts arising in connection with the transactions contemplated by the merger agreement.

Novacap Cadent Acquisition Company, Inc., a Delaware corporation and an indirect holding company of Parent (which we refer to as the “Borrower”), was formed on June 26, 2023. Borrower’ principal executive offices are located at 1675 Broadway, 22^nd floor, New York, New York, 10019. Parent’s telephone number is (212) 796-1960.

Novacap Cadent Holdings, Inc., a Delaware corporation, and an indirect holding company of Parent and a direct holding company of Borrower (which we refer to as “Holdings”), was formed on June 26, 2023. Holdings’ principal executive offices are located at 1675 Broadway, 22^nd floor, New York, New York, 10019. Holdings’ telephone number is (212) 796-1960.

For more information, see the section entitled “The Merger—Financing of the Merger” beginning on page 66 of this proxy statement.

At the special meeting, you will be asked to consider and vote upon a proposal to adopt the Agreement and Plan of Merger (which we refer to as the “merger agreement”), which was entered into on April 1, 2024, by and among the Company, Parent, Merger Sub, Borrower and Holdings. Pursuant to the merger agreement, Merger Sub will merge with and into AdTheorent (which we refer to as the “merger”), with AdTheorent surviving the merger and becoming a wholly-owned subsidiary of Parent. If the merger is completed, you will be entitled to receive $3.21 in cash, without interest (which we refer to as the “per share merger consideration”), subject to applicable withholding taxes, for each share of Company common stock you own as of immediately prior to the effective time of the merger (which we refer to as the “effective time”), other than (i) any shares owned by the Company and any shares owned by Parent or Merger Sub (or any of their respective affiliates); (ii) 598,875 shares subject to the Escrow Agreement dated December 22, 2021 by and among AdTheorent Holding Company, Inc., MCAP Acquisition, LLC, and Continental Stock Transfer & Trust Company, as amended by Amendment to Stock Escrow Agreement dated January 24, 2024 (which we refer to as the “escrow agreement”), (iii) 1,167,308 shares subject to forfeiture under the voting and support agreement dated April 1, 2024 by and among H.I.G. Growth – AdTheorent, LLC, the Company, Parent and Merger Sub (which we refer to as the “H.I.G. support agreement”) and (iv) any shares as to which appraisal rights have been perfected (and not withdrawn or lost) in accordance with applicable law (which will be cancelled and converted into the right to receive a payment determined in accordance with Section 262 of the Delaware General Corporation Law (which we refer to as the “DGCL”)).

In connection with the execution of the merger agreement, on April 1, 2024, H.I.G. Growth – AdTheorent, LLC (“H.I.G. AdTheorent”), in its capacity as a stockholder of the Company, holding approximately 37% of the outstanding shares of Company common stock in the aggregate, has executed and delivered the H.I.G. support agreement pursuant to which it agreed, among other things, to vote its respective shares of Company common stock in favor of the Merger and against certain actions that would prevent, interfere with or delay the consummation of the merger (the “H.I.G. support agreement”).

Pursuant to the H.I.G. support agreement, in connection with the execution of the merger agreement, immediately prior to, and conditioned upon the occurrence of, the effective time, H.I.G. AdTheorent agreed to forfeit 1,167,308 shares of common stock to the Company for cancellation for no consideration (resulting in a forfeiture of, in aggregate, $3,747,058.68 of the merger consideration based on the $3.21 per share merger consideration) (the “forfeiture”). The Company and H.I.G. AdTheorent agreed that the forfeiture shall be treated as a nontaxable contribution to the capital of the Company made by H.I.G. AdTheorent, and neither H.I.G. AdTheorent nor the Company shall take any position inconsistent with such treatment unless otherwise required under the Internal Revenue Code of 1986, as amended (the “Code”).

Also in connection with the execution of the merger agreement, on April 1, 2024, (1) James Lawson, in his capacity as a stockholder of the Company and not in his capacity as a director or Chief Executive Officer of the Company, representing approximately 2.1% of the outstanding shares of Company common stock, (2) Patrick Elliott, in his capacity as a stockholder of the Company and not in his capacity as Chief Financial Officer of the Company, representing approximately <1% of the outstanding shares of Company common stock, (3) William Todd, in his capacity as a stockholder of the Company and not in his capacity as Chief Revenue Officer of the Company, representing approximately <1% of the outstanding shares of Company common stock, (4) Andrew Anderson, in his capacity as a stockholder of the Company and not in his capacity as Chief Technology Officer of the Company, representing approximately <1% of the outstanding shares of Company common stock, (5) Kihara Kiarie, in his capacity as a stockholder of the Company and not in his capacity as a director of the Company, representing approximately <1% of the outstanding shares of Company common stock, (6) Vineet Mehra, in his capacity as a stockholder of the Company and not in his capacity as a director of the Company, representing approximately <1% of the outstanding shares of Company common stock, (7) Ben Tatta in his capacity as a stockholder of the Company and not in his capacity as a director of the Company, representing approximately <1% of the outstanding shares of Company common stock, and (8) John Black, in his capacity as a stockholder of the Company and not in his capacity as a director of the Company, representing approximately <1% of the outstanding shares of Company common stock, have executed and delivered voting and support agreements in favor of Parent and Merger Sub, pursuant to which they agreed, among other things, to vote their respective shares of Company common stock in favor of the Merger and against certain actions that would prevent, interfere with or delay the consummation of the Merger (collectively, the “company support agreements,” and, with the H.I.G. support agreement, the “support agreements”).

The support agreements will terminate upon the earliest to occur of (i) the valid termination of the merger agreement pursuant to Article 8 thereof, (ii) the effective time, (iii) the termination of the support agreement by mutual written consent of the parties thereto and (iv) in the event the Board makes an Adverse Recommendation Change (as defined in the merger agreement), except that in such case, the H.I.G. support agreement will not be terminated, but the number of shares of Company common stock to which the support obligations apply under the H.I.G. support agreement will be reduced to 35% of the outstanding shares of Company common stock.

See “The Support Agreements” beginning on page 94 of this proxy statement.

The special meeting will be held on [•], 2024, at [•] a.m. Eastern Time, at 330 Hudson Street, 13th Floor, New York, NY 10013.

Only individuals who were AdTheorent stockholders of record at the close of business on [•], 2024 (which we refer to as the “record date”) are entitled to notice of the special meeting and to vote at the special meeting or at any adjournment or postponement thereof. The presence at the special meeting, in person or by proxy, of the holders of record of a majority of the shares of Company common stock issued and outstanding at the close of business on the record date will constitute a quorum, permitting AdTheorent to conduct its business at the special meeting.

Holders of Company common stock are entitled to one vote on each proposal submitted to a vote at the special meeting for each share of Company common stock they own at the close of business on the record date.

For AdTheorent to complete the merger, stockholders holding a majority of the shares of Company common stock issued and outstanding at the close of business on the record date, must vote “FOR” the proposal to adopt the merger

agreement. A failure to vote your shares of Company common stock or an abstention from voting on the proposal to adopt the merger agreement will have the same effect as a vote “AGAINST” the proposal to adopt the merger agreement. If your shares are held in street name by your broker, bank or other nominee, and you do not instruct the nominee how to vote your shares, a “broker non-vote” will arise and will have the same effect as a vote “AGAINST” the proposal to adopt the merger agreement.

For stockholders to adjourn the special meeting, stockholders holding not less than a majority of the shares of Company common stock, present in person or represented by proxy at the meeting and entitled to vote thereon, must vote “FOR” the proposal to adjourn the special meeting. An abstention from voting on the proposal to adjourn the special meeting will have the same effect as a vote “AGAINST” the proposal to adjourn the special meeting. If your shares are held in street name by your broker, bank or other nominee and you do not instruct the nominee how to vote your shares, a “broker non-vote” will arise but will have no effect on this proposal, assuming a quorum is present.

At the close of business on the record date, there were [•] shares of Company common stock issued and outstanding.

See the description of the support agreements above.

If you are a stockholder of record, you may vote your shares using one of the four methods described below.

Before the special meeting, go to www.proxyvote.com. Use the Internet to transmit your voting instructions for electronic delivery of information up until 11:59 p.m. Eastern Time the day before the meeting date. You will need the 16-digit control number found on your proxy card or voting instruction form.

During the special meeting, go to www.virtualshareholdermeeting.com/ADTH2024SM. You may attend the meeting via the Internet and vote during the meeting. Have your proxy card in hand and follow the instructions;

Use any touch-tone telephone to transmit your voting instructions up until 11:59 p.m. Eastern Time the day before the meeting date. Have your proxy card in hand when you call and then follow the instructions;

You can vote by mail by marking, dating, and signing your proxy card or voting instruction form and returning it in the postage-paid envelope at least two business days before the meeting date; or

You may also vote in person at the special meeting.

If you are a beneficial owner of shares held in street name, you will receive instructions from your broker, bank or other nominee as to how to vote your shares. You must follow the instructions of your broker, bank or other nominee in order for your shares to be voted. Telephone and internet voting also will be offered to stockholders owning shares through certain brokers, banks and other nominees. If your shares are not registered in your own name but are held through your broker, bank or other nominee and you plan to vote your shares in person at the special meeting, you should contact your broker, bank or other nominee to obtain a “legal proxy” or broker’s proxy card and bring it to the special meeting in order to vote. If you hold your shares through a broker, bank or other nominee, such nominee cannot vote your shares unless you have given your nominee specific instructions as to how to vote.

The merger agreement provides that the closing of the merger (which we refer to as the “closing”) will take place at 9:00 AM Eastern Time, as soon as practicable (and, in any event, within three business days, and provided further that such date shall be a business day on which the Division of Corporations of the Department of State of the State of Delaware is open for business) after satisfaction or, to the extent permitted under the merger agreement, waiver of all conditions to the merger set forth in Article 7 of the merger agreement (other than those conditions that by their nature are to be satisfied at the closing, but subject to the satisfaction or waiver, to the extent permitted under the merger agreement, of such conditions), unless the merger agreement has been terminated pursuant to its terms or unless another time or date is agreed to in writing by the parties thereto.

As soon as practicable on the closing date of the merger (which we refer to as the “closing date”), AdTheorent and Parent will cause a certificate of merger to be executed and delivered to the Secretary of State of the State of Delaware for filing as provided under the DGCL. The merger will become effective on such date and at such time when the certificate of merger has been filed with the Secretary of State of the State of Delaware or on such later date or at such later time as may be agreed to by AdTheorent, Parent and Merger Sub and is specified in the certificate of merger.

The respective obligations of the Company, Parent and Merger Sub to consummate the merger and the other transactions contemplated by the merger agreement are subject to the satisfaction or, to the extent permitted by applicable law, waiver of, at or prior to the closing, of the following conditions:

The respective obligations of Parent and Merger Sub to consummate the merger and the other transactions contemplated by the merger agreement are subject to the satisfaction or, to the extent permitted by applicable law, waiver by Parent of, at or prior to the closing, of the following additional conditions:

The obligations of the Company to consummate the merger and the other transactions contemplated by the merger agreement are subject to the satisfaction or, to the extent permitted by applicable law, waiver, at or prior to the closing, of the following additional conditions:

For more information, please see “The Merger Agreement—Other Covenants and Agreements—Conditions to the Merger” beginning on page 89 of this proxy statement.

If the merger agreement is not adopted by the Company’s stockholders, or if the merger is not consummated for any other reason:

In addition, if the merger is not consummated under certain special circumstances set forth in the merger agreement and described herein under “The Merger Agreement—Termination,” AdTheorent may be required to pay Parent a termination fee equal to $11,355,513 (provided that if the merger agreement is terminated under certain specified circumstances during the go-shop period or pursuant to certain transactions with a go-shop party after the expiration of the go-shop period, and notice of such superior proposal termination has been provided to Parent before

11:59 p.m. Eastern Time on May 17, 2024, the Company will be required to pay Parent a termination fee of $6,488,865). For more information, please see “The Merger—Effect on AdTheorent if the Merger is Not Consummated” beginning on page 36 of this proxy statement.

The Board unanimously recommends that AdTheorent stockholders vote “FOR” the proposal to adopt the merger agreement and “FOR” the other proposals to be considered at the special meeting. For a description of the reasons considered by the Board in deciding to recommend the adoption of the merger agreement, see the section entitled “The Merger—Recommendation of the Board and Reasons for the Merger” beginning on page 46 of this proxy statement.

In connection with the Board’s consideration of the merger agreement, on March 28, 2024, representatives of Canaccord Genuity LLC (“Canaccord”) orally delivered to the Board Canaccord’s opinion to the effect that, as of the date of such opinion and based upon and subject to the various assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of review undertaken by Canaccord as set forth in its written opinion, a copy of such written opinion is included as Annex B to this proxy statement, the merger consideration of $3.21 per share in cash to be received by the holders of Company common stock (other than shares of common stock of the Company owned by the Company, Parent, Merger Sub, or any of their respective affiliates or held by holders exercising appraisal rights described in Section 2.05 of the merger agreement) in the merger pursuant to the merger agreement was fair, from a financial point of view, to such holders, and after the meeting provided the Board with Canaccord’s written opinion. The full text of Canaccord’s written opinion is attached to this proxy statement as Annex B and is incorporated herein by reference. The description of Canaccord’s opinion set forth in this proxy statement is qualified in its entirety by reference to the full text of such opinion. Stockholders of AdTheorent are encouraged to read Canaccord’s opinion carefully and in its entirety for a description of the various assumptions made, procedures followed, matters considered, and qualifications and limitations on the review undertaken by Canaccord in connection with its opinion. Canaccord’s opinion was addressed to the Board of Directors of AdTheorent (the “AdTheorent Board”), was only one of many factors considered by the AdTheorent Board in its evaluation of the merger, and is limited to and addresses only the fairness, from a financial point of view and as of the date of the opinion, to the holders of shares of Company common stock (other than the Company, Parent, Merger Sub or any of their respective Affiliates or holders exercising appraisal rights described in Section 2.05 of the Agreement) of the per share merger consideration to be received by such holders pursuant to the merger agreement. Canaccord’s opinion does not address the relative merits of the merger as compared to other business strategies or transactions that might be available to AdTheorent, nor does it address the underlying business decision of AdTheorent to proceed with the merger or any view on another term or aspect of the merger. Canaccord’s opinion was solely directed to and for the information of the AdTheorent Board in connection with its evaluation of the merger and did not constitute advice or a recommendation to the AdTheorent Board as to how the AdTheorent Board should vote with respect to the merger agreement and does not constitute advice or a recommendation to any holder of Company common stock as to how such person should otherwise act with respect to the merger or any other matter. Canaccord’s opinion was rendered on the basis of securities, economic, market and monetary conditions prevailing as of March 28, 2024, the date of its opinion, and on the prospects, financial and otherwise, of AdTheorent known to Canaccord as of such date. Subsequent developments may affect the conclusions expressed in Canaccord’s opinion if such opinion were rendered as of a later date. Canaccord disclaims any obligation to advise any person of any change in any manner affecting its opinion that may come to its attention after the date of its opinion. Canaccord has not undertaken to reaffirm or revise its opinion or otherwise comment on any events occurring after the date of its opinion and does not have any obligation to update, revise or reaffirm its opinion.

For a description of the opinion that the Board received from Canaccord, see “The Merger—Opinion of Canaccord Genuity LLC” beginning on page 52 of this proxy statement.

Immediately prior to the effective time, by virtue of the merger, each award of restricted stock units (which we refer to as “Company RSUs”) granted under the Company’s 2021 Long-Term Incentive Plan (together with the AdTheorent Holding Company, LLC 2017 Interest Option Plan, the “Company Equity Plans”) that is outstanding immediately prior to the effective time will automatically be cancelled and converted into the right to receive a cash

payment in an amount, without interest thereon and subject to applicable withholding taxes, equal to the product of (i) the per share merger consideration and (ii) the total number of shares of Company common stock subject to such award of Company RSUs as of immediately prior to the effective time.

Immediately prior to the effective time, by virtue of the merger, each award of a company stock option (which we refer to as “Company Stock Options”) granted under a Company Equity Plan that is outstanding immediately prior to the effective time will automatically be cancelled and converted into the right to receive a cash payment in an amount, without interest thereon and subject to applicable withholding taxes, equal to the product of (i) the amount by which (A) the per share merger consideration exceeds (B) the per share exercise price of such Company Stock Option, multiplied by (ii) the total number of shares of Company common stock subject to such Company Stock Option as of immediately prior to the effective time. If the per share exercise price equals or exceeds the per share merger consideration, such Company Stock Option will be cancelled for no consideration as of immediately prior to the effective time.

The Company Board has adopted such resolutions as are necessary to provide that, with respect to the MCAP Acquisition Corporation 2021 Employee Stock Purchase Plan, adopted on December 21, 2021 (the “Company ESPP”): (i) the Company ESPP is suspended such that (A) no new offering or purchase period will commence following the date of the merger agreement; (B) an employee who is not a participant in the Company ESPP as of the date of the merger agreement will not be permitted to become a participant in the Company ESPP after the date of the merger agreement; and (C) no participant may increase his or her contributions (including making any non-payroll contributions) with respect to the offering in effect as of the date of the merger agreement; (ii) the offering in effect as of the date of the merger agreement will end on the earlier of its regularly scheduled end date and 14 business days prior to the expected effective time (such date, the “offering termination date”); (iii) each participant’s outstanding purchase right will automatically be exercised on the offering termination date; and (iv) the Company ESPP will, contingent upon the occurrence of the closing of the merger, be terminated effective as of the date immediately prior to the date on which the effective time occurs, and no further rights shall be granted or exercised under the Company ESPP thereafter.

The directors and executive officers of AdTheorent (including John Black, Danielle Qi, Eric Tencer and Shuangxiu Yu, the four (4) directors nominated to the Board by H.I.G. Growth – AdTheorent, LLC, a stockholder of AdTheorent holding approximately 37.2% of the outstanding shares of AdTheorent common stock as of the record date, pursuant to the Stockholders Agreement, dated as of December 22, 2021, by and among AdTheorent, H.I.G. Growth – AdTheorent, LLC, MCAP Acquisition, LLC, and the other parties thereto) have interests in the merger that may be different from, or in addition to, the interests of AdTheorent stockholders generally. These interests are described in more detail in the section entitled “The Merger—Interests of AdTheorent’s Directors and Executive Officers in the Merger” beginning on page 61 of this proxy statement. The Board was aware of these interests prior to the execution of the merger agreement and considered them, among other matters, in approving the merger agreement and in determining to recommend that the stockholders adopt the merger agreement. These interests may include the following, among others:

The obligation of Parent and Merger Sub to consummate the merger is not subject to a financing condition. Parent plans to fund the transactions contemplated by the merger agreement (including payment of the aggregate consideration and payment of the costs, fees, expenses and other amounts arising in connection with the transactions contemplated by the merger agreement) with committed equity and debt financing.

In connection with the execution and delivery of the merger agreement, Parent entered into an equity commitment letter, dated as of April 1, 2024, with the Novacap Equity Investors (which letter we refer to as the “equity commitment letter”). The Novacap Equity Investors have committed to contribute to Parent an aggregate amount in

cash of up to $94,030,265, upon the terms and subject to conditions set forth in the equity commitment letter, which equity commitments will be used by Parent, together with the debt financing described below, to fund Parent’s obligations under the merger agreement. The Novacap Equity Investors’ equity commitments are subject only to the satisfaction or waiver of the conditions to Parent and Merger Sub’s obligations to effect the consummation of the merger as set forth in the merger agreement, the prior or substantially concurrent funding of the debt financing (or any alternate debt financing in accordance with the merger agreement) as contemplated by the merger agreement and the contemporaneous consummation of the closing. AdTheorent is an express third-party beneficiary of the equity commitment letter and is entitled to enforce Parent’s right to cause the commitments under the equity commitment letter to be funded to Parent in accordance with the equity commitment letter, subject to the limitations and conditions set forth in the equity commitment letter.

In addition to the equity commitment letter, in connection with the execution and delivery of the merger agreement, Novacap has entered into and delivered to the Company: (i) an executed subordinated note (the “subordinated note”), pursuant to which the financing sources party thereto have committed to provide Parent with debt financing in an amount of up to $80,000,000 and (ii) an executed amendment to the Credit Agreement (the “debt commitment letter”), by and among Novacap Cadent Acquisition Company, Inc., a Delaware corporation, as borrower (the “Borrower”), Novacap Cadent Holdings, Inc., as a guarantor (“Holdings”), the guarantors party thereto, the lenders party thereto and Royal Bank of Canada, as administrative agent and collateral agent for the lenders, pursuant to which the lenders have made available an additional $140,000,000 of debt financing.

For more information, please see the section entitled “The Merger—Financing of the Merger” beginning on page 66 of this proxy statement.

The exchange of shares of Company common stock for the merger consideration pursuant to the merger will be a taxable transaction for U.S. federal income tax purposes. Accordingly, an AdTheorent stockholder that is a U.S. holder (as defined in the section entitled “The Merger—Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 66 of this proxy statement) generally will recognize taxable gain or loss in an amount equal to the difference, if any, between (i) the amount of cash received by such U.S. holder in the merger and (ii) such U.S. holder’s adjusted tax basis in the shares of Company common stock exchanged therefor. With respect to an AdTheorent stockholder that is a non-U.S. holder (as defined in the section entitled “The Merger—Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 66 of this proxy statement), the exchange of shares of Company common stock for the merger consideration pursuant to the merger generally will not result in U.S. federal income tax to such non-U.S. holder, unless such non-U.S. holder has certain connections with the United States or AdTheorent is, or was during the relevant period, a “United States real property holding corporation” within the meaning of Section 897(c)(2) of the Code. We believe that we are not, nor have we been during the relevant period, a United States real property holding corporation. Backup withholding may apply to the cash payments made pursuant to the merger, unless the AdTheorent stockholder or other payee provides a valid taxpayer identification number and complies with certain certification procedures (generally, by providing a properly completed and executed U.S. Internal Revenue Service (“IRS”) Form W-9 or IRS Form W-8 or applicable successor form).

Each AdTheorent stockholder is urged to read the discussion in the section entitled “The Merger—Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 66 of this proxy statement, and to consult its, his or her tax advisor to determine the U.S. federal, state or local or non-U.S. income or other tax consequences to it, him or her of the merger in light of its, his or her particular circumstances and any consequences arising under any state, local or non-U.S. tax law or tax treaties.

Under the terms of the merger agreement, the merger cannot be completed until the waiting period applicable to the merger under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (which we refer to as the “HSR Act”), has expired or been terminated. AdTheorent and Parent filed or caused to be filed their respective HSR Act notifications on April 5, 2024.

Under the DGCL, AdTheorent stockholders and beneficial owners who do not vote for the adoption of the merger agreement will have the right to seek appraisal of the fair value of their shares as determined by the Delaware Court of Chancery, but only if they fully comply with all of the applicable requirements of the DGCL, which are

summarized in this proxy statement. Any appraisal amount determined by the court could be more than, the same as or less than the value of the merger consideration. Any stockholder or beneficial owner intending to exercise appraisal rights must, among other things, submit a written demand for appraisal to AdTheorent before the vote on the adoption of the merger agreement and must not vote or otherwise submit a proxy in favor of the adoption of the merger agreement. Failure to follow exactly the procedures specified under the DGCL will result in the loss of appraisal rights. Because of the complexity of the DGCL relating to appraisal rights, if you are considering exercising your appraisal rights, we encourage you to seek the advice of your own legal counsel. The discussion of appraisal rights contained in this proxy statement is not a full summary of the law pertaining to appraisal rights under the DGCL and is qualified in its entirety by the full text of Section 262 of the DGCL that is attached as Annex C to this proxy statement. A copy of Section 262 of the DGCL is also accessible at the following publicly available website: https://delcode.delaware.gov/title8/c001/sc09/index.html#262.

The content of the website referred to above is not incorporated into this proxy statement. Further, our reference to the URL for this website is intended to be an inactive textual reference only.

If the merger is completed, Company common stock will be de-listed from Nasdaq and de-registered under the Exchange Act.

For purposes of this proxy statement, each of “acceptable confidentiality agreement,” “acquisition proposal” and “superior company proposal” is defined in the section entitled “The Merger Agreement—Other Covenants and Agreements—Go-Shop; Unsolicited Proposals” beginning on page 80 of this proxy statement.

Beginning on the date of the merger agreement and continuing until 11:59 p.m. Eastern Time on May 4, 2024 (which we refer to as the “go-shop period”), the Company and its representatives had the right to, subject to certain conditions in the merger agreement: (1) solicit, initiate, facilitate and encourage any inquiry, proposal or offer that could constitute an alternative acquisition proposal from third parties; (2) furnish non-public information to such third parties in connection with any such proposal; and (3) participate in discussions or negotiations with third parties with respect to such proposals.

Following the expiration of the go-shop period at 11:59 p.m. Eastern Time on May 4, 2024, the Company will be restricted from soliciting alternative acquisition proposals, engaging in discussions or negotiations with respect to such proposals or providing non-public information in connection with such proposals, subject to certain limited exceptions to permit the Board to comply with its fiduciary duties.

In the event that the Board receives an alternative acquisition proposal that it determines to be a superior company proposal in accordance with the terms of the merger agreement, the Company may, subject to compliance with requirements to provide notice to and a period for Parent to match such proposal, payment of the Company termination fee by the Company to Parent described below and other conditions and requirements set forth in the merger agreement, withdraw its recommendation in favor of the adoption of the merger agreement and terminate the merger agreement to accept the applicable superior company proposal.

Additionally, subject to certain customary “fiduciary exceptions,” the Board is not permitted to withdraw, qualify, amend or modify, in each case in any manner adverse to Parent or Merger Sub, its recommendation that the Company’s stockholders adopt the merger agreement.

For a more complete description, please see the section entitled “The Merger Agreement—Other Covenants and Agreements—Go-Shop; Unsolicited Proposals” beginning on page 80 of this proxy statement.

For purposes of this proxy statement, each of “adverse recommendation change” and “intervening event” is defined in the section entitled “The Merger Agreement—Other Covenants and Agreements—Company Board Recommendation Change; Adverse Recommendation Change; Fiduciary Exception” beginning on page 82 of this proxy statement.

As described above, the Board has made the recommendation that the Company’s stockholders vote “FOR” the proposal to adopt the merger agreement. Under the merger agreement, in certain circumstances and subject to certain

limitations set forth in the merger agreement, if the Board determines in good faith (after consultation with the Company’s outside legal counsel), that failure to do so would reasonably be expected to be inconsistent with the fiduciary duties of the Board under Delaware law, the Board may make an adverse recommendation change in response to either (i) a superior company proposal received after the date of the merger agreement or (ii) an intervening event that was not known by the Board prior to or as of the date of the merger agreement.

For a more complete description, please see the section entitled “The Merger Agreement—Other Covenants and Agreements—Company Board Recommendation; Adverse Recommendation Change; Fiduciary Exception” beginning on page 82 of this proxy statement.

The merger agreement may be terminated and the transactions contemplated by the merger agreement may be abandoned at any time prior to the closing:

In the event of (i) a superior proposal termination, (ii) a recommendation change termination or (iii) provided that an alternative acquisition agreement with respect to an acquisition proposal made to the Company prior to a company breach termination is executed within 12 months of termination, a company breach termination, the Company will pay to Parent, by wire transfer of same-day funds to an account designated by Parent, (A) in the case of (i) above, prior to or concurrently with such superior proposal termination, (B) in the case of (ii) above, within two business days after such recommendation change termination, and, in the case of (iii) above, prior to or concurrently with (and subject to) the consummation of the transactions contemplated by such alternative acquisition agreement, a termination fee equal to $11,355,513, provided, however, that such termination fee will be equal to $6,488,865 in the case of a termination pursuant to clause (i) above if the superior proposal termination relates to a superior company proposal from a go-shop party and notice of such superior proposal termination has been provided to Parent before 11:59 p.m. Eastern Time on May 17, 2024 (such fee, in either case, the “Company Termination Fee”).

The collective monetary damages payable by Parent and its related parties for breaches under this merger agreement, the debt commitment letter, the subordinated note or the equity commitment letter may not exceed an amount equal to $32,444,323 in the aggregate for all such breaches.

Except as otherwise provided in the merger agreement, whether or not the merger is consummated, all expenses incurred in connection with the merger agreement will be paid by the party incurring or required to incur such expenses. Parent is responsible for paying all filing fees payable pursuant to the HSR Act and any other antitrust laws.

Each of the parties is entitled to an injunction or injunctions to prevent breaches of the merger agreement or to enforce specifically the performance of the terms and provisions, in addition to any other remedy to which they are entitled at applicable law or in equity in connection with the merger agreement.

The Company is entitled to an injunction, specific performance or other equitable remedy to specifically enforce Parent’s and Merger Sub’s obligations under the merger agreement, including their obligation to effect the closing in

the event and only in the event that each of the following requirements has been satisfied: (i) the conditions set forth in the merger agreement have been satisfied or waived at the time the closing would have occurred, but for the failure of the equity financing to be funded, and the conditions remain satisfied; (ii) the debt financing has been funded in accordance with the terms thereof or will be or would be funded in accordance with the terms thereof at the closing if the equity financing was funded at the closing; and (iii) the Company has confirmed in writing to Parent that if specific performance is granted and the equity financing and debt financing are funded, then the closing will occur.

By seeking the remedies listed above, a party does not, in any respect, waive its right to seek any other form of relief that may be available to a party under the merger agreement (including fraud remedies). Nothing within the merger agreement shall require any party to institute any proceeding for specific performance or as a condition to exercising termination rights.

Company common stock is listed on Nasdaq under the symbol “ADTH.” The closing sale price of Company common stock on March 28, 2024, the last trading day prior to the execution of the merger agreement, was $3.21 per share. On [•], 2024, the most recent practicable date before the filing of this proxy statement, the closing price of Company common stock was $[•] per share. You are encouraged to obtain current market quotations for our common stock in connection with voting your shares of our common stock.

For a more complete description, please see the section entitled “Market Prices” beginning on page 97 of this proxy statement.

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Neither the SEC nor any state securities regulatory agency has approved or disapproved of the transactions described in this document, including the merger, or determined if the information contained in this document is accurate or adequate. Any representation to the contrary is a criminal offense.