Filed by South Mountain Merger Corp.

Pursuant to Rule 425 under the Securities Act of 1933

and deemed filed pursuant to Rule 14a-12

under the Securities Exchange Act of 1934

Subject Company: South Mountain Merger Corp.

Commission File No. 001-38947

Date: November 13, 2020

   Investor Presentation  November 2020 

 Disclaimers  This presentation is provided for informational purposes only and has been prepared to assist interested parties in making their own evaluation with respect to a potential business combination (the “proposed business combination”) between Factor Systems, Inc. (d/b/a Billtrust) (“Billtrust”) and South Mountain Merger Corp. (“South Mountain”) and related transactions (the “Transactions”) and for no other purpose. No representations or warranties, express or implied are given in, or in respect of, this presentation. Industry and market data used in this presentation have been obtained from third-party industry publications and sources as well as from research reports prepared for other purposes. Neither Billtrust nor South Mountain has independently verified the data obtained from these sources and cannot assure you of the data’s accuracy or completeness. This data is subject to change. In addition, this presentation does not purport to be all-inclusive or to contain all of the information that may be required to make a full analysis of Billtrust or the Transactions. Viewers of this presentation should each make their own evaluation of Billtrust and of the relevance and adequacy of the information and should make such other investigations as they deem necessary. Forward-Looking Statements This presentation includes “forward-looking statements” within the meaning of the “safe harbor” provisions of the United States Private Securities Litigation Reform Act of 1995. Forward-looking statements may be identified by the use of words such as “estimate,” “plan,” “project,” “forecast,” “intend,” “will,” “expect,” “anticipate,” “believe,” “seek,” “target” or other similar expressions that predict or indicate future events or trends or that are not statements of historical matters. These forward-looking statements include, but are not limited to, statements regarding estimates and forecasts of financial and performance metrics, projections of market opportunity and market share, potential benefits and the commercial attractiveness to its customers of Billtrust’s products and services, the potential success of Billtrust’s marketing and expansion strategies, the growth of demand on Billtrust’s platform and the expansion of Billtrust’s customers’ utilization of its services, potential benefits of the Transactions (including with respect to shareholder value), and expectations related to the terms and timing of the Transactions. These statements are based on various assumptions, whether or not identified in this presentation, and on the current expectations of Billtrust’s and South Mountain’s management and are not predictions of actual performance. These forward-looking statements are provided for illustrative purposes only and are not intended to serve as, and must not be relied on by any investor as, a guarantee, an assurance, a prediction or a definitive statement of fact or probability. Actual events and circumstances are difficult or impossible to predict and will differ from assumptions. Many actual events and circumstances are beyond the control of Billtrust and South Mountain. These forward-looking statements are subject to a number of risks and uncertainties, including Billtrust’s ability to attract and retain customers and expand customers’ use of Billtrust’s services; market, financial, political and legal conditions; the impact of the COVID-19 pandemic on Billtrust’s business and the global economy; the inability of the parties to successfully or timely consummate the proposed business combination, including the risk that any required regulatory approvals are not obtained, are delayed or are subject to unanticipated conditions that could adversely affect the combined company or the expected benefits of the proposed business combination or that the approval of the stockholders of South Mountain or Billtrust is not obtained; failure to realize the anticipated benefits of the proposed business combination; risks relating to the uncertainty of the projected financial and operating information with respect to Billtrust; risks related to future market adoption of Billtrust's offerings; risks related to Billtrust's marketing and growth strategies; the effects of competition on Billtrust’s future business; the amount of redemption requests made by South Mountain’s public stockholders; the ability of South Mountain or the combined company to issue equity or equity-linked securities in connection with the proposed business combination or in the future, and those factors discussed in South Mountain’s final prospectus filed on June 21, 2019, Annual Report on Form 10-K for the fiscal year ended December 31, 2019 and Quarterly Reports on Form 10-Q for the quarters ended March 31, 2020 and June 30, 2020, in each case, under the heading “Risk Factors,” and other documents of South Mountain filed, or to be filed, with the Securities and Exchange Commission (“SEC”). If any of these risks materialize or any of South Mountain’s or Billtrust’s assumptions prove incorrect, actual results could differ materially from the results implied by these forward-looking statements. There may be additional risks that neither South Mountain nor Billtrust presently know or that South Mountain and Billtrust currently believe are immaterial that could also cause actual results to differ from those contained in the forward-looking statements. In addition, forward-looking statements reflect South Mountain’s and Billtrust’s expectations, plans or forecasts of future events and views as of the date of this presentation. South Mountain and Billtrust anticipate that subsequent events and developments will cause South Mountain’s and Billtrust’s assessments to change. However, while South Mountain and Billtrust may elect to update these forward-looking statements at some point in the future, South Mountain and Billtrust specifically disclaim any obligation to do so. These forward-looking statements should not be relied upon as representing South Mountain’s and Billtrust’s assessments as of any date subsequent to the date of this presentation. Accordingly, undue reliance should not be placed upon the forward-looking statements. Use of Projections This presentation contains projected financial information with respect to Billtrust, namely total revenues, net revenue (non-GAAP), adjusted gross profit, adjusted gross margin, and net revenue (non-GAAP) split for 2020, 2021, 2022, and the financial information included in Billtrust’s long-term target operating model. Such projected financial information constitutes forward-looking information and is for illustrative purposes only and should not be relied upon as necessarily being indicative of future results. The assumptions and estimates underlying such projected financial information are inherently uncertain and are subject to a wide variety of significant business, economic, competitive and other risks and uncertainties that could cause actual results to differ materially from those contained in the prospective financial information. See “Forward-Looking Statements” above. Actual results may differ materially from the results contemplated by the projected financial information contained in this presentation, and the inclusion of such information in this presentation should not be regarded as a representation by any person that the results reflected in such projections will be achieved. Neither of the independent registered public accounting firms of Billtrust or South Mountain have audited, reviewed, compiled, or performed any procedures with respect to the projections for the purpose of their inclusion in this presentation, and accordingly, neither of them expressed an opinion or provided any other form of assurance with respect thereto for the purpose of this presentation.Financial Information; Non-GAAP Financial Measures The financial information and data contained in this presentation is unaudited and does not conform to Regulation S-X. Billtrust is in the process of completing its Public Company Accounting Oversight Board (“PCAOB”) audits for the fiscal years ended December 31, 2017, 2018 and 2019 and the review procedures for the six months ended June 30, 2019 and June 30, 2020, respectively, and, therefore, all of Billtrust’s historical financial information included in the presentation is preliminary and subject to change. Billtrust’s independent registered public accounting firm, BDO USA, has not audited or reviewed, and does not express an opinion with respect to, any of the financial information or data included in this presentation. The financial information included in this presentation is not a comprehensive statement of Billtrust’s financial results for the periods shown, and Billtrust’s actual results may differ materially from the financial information included in this presentation due to the completion of Billtrust’s financial closing procedures, final adjustments, completion of the audits and review of Billtrust’s financial statements referenced above and other developments that may arise between now and the time those audits and review are completed. Accordingly, the financial information and data contained in this presentation may not be included in, may be adjusted in or may be presented differently in, any proxy statement, registration statement, or prospectus to be filed by South Mountain with the SEC. 

 Disclaimers (cont’d)  Further, some of the financial information and data contained in this presentation, such as net revenue (non-GAAP), adjusted gross profit, adjusted gross margin, EBITDA, EBITDA margin, Adjusted EBITDA, Adjusted EBITDA margin, free cash flow, free cash flow margin, net recurring revenue percentage, and the financial information included in Billtrust’s long-term target operating model, have not been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”). Net revenue (non-GAAP) is defined as total revenues, less reimbursable costs revenue. Adjusted Gross Margin is defined as Billtrust’s Adjusted Gross Profit divided by its total revenues less reimbursable costs revenue, or net revenue (non-GAAP). EBITDA is defined as net profit/(loss) plus depreciation and amortization expenses, income tax expense/(benefit) and other expense/(income). EBITDA margin is defined as EBITDA divided by net revenue (non-GAAP). Adjusted EBITDA is defined as Net loss and comprehensive loss, plus (i) provision (benefit) for income taxes, (ii) interest and other expense (income), (iii) interest expense, (iv) depreciation and amortization, (v) stock based compensation expense, (vi) restructuring and severance costs, and (vii) acquisition and integration costs. Adjusted EBITDA margin is defined as Adjusted EBITDA divided by net revenue (non-GAAP). Free cash flow is defined as net cash used in operating activities less purchases of property and equipment, and less capitalization of internal-use software costs. Free cash flow margin is defined as free cash flow divided by net revenue (non-GAAP). Net recurring revenue percentage is defined as subscription and transaction fees divided by net revenue (non-GAAP).South Mountain and Billtrust believe these non-GAAP measures of financial results provide useful information to management and investors regarding certain financial and business trends relating to Billtrust’s financial condition and results of operations. South Mountain and Billtrust believe that the use of these non-GAAP financial measures provides an additional tool for investors to use in evaluating actual and projected operating results and trends in and in comparing Billtrust’s financial measures with other similar companies, many of which present similar non-GAAP financial measures to investors. Neither South Mountain nor Billtrust considers these non-GAAP measures in isolation or as an alternative to financial measures determined in accordance with GAAP. The principal limitation of these non-GAAP financial measures is that they exclude significant expenses and other amounts that are required by GAAP to be recorded in Billtrust’s financial statements. In addition, they are subject to inherent limitations as they reflect the exercise of judgments by management about which expense and other amounts are excluded or included in determining these non-GAAP financial measures. In order to compensate for these limitations, Billtrust presents non-GAAP financial measures in connection with GAAP results. Billtrust is not providing a reconciliation of its projected net revenue (non-GAAP) split for full years 2020, 2021, 2022 or the financial information included in Billtrust’s long-term target operating model to the most directly comparable measure prepared in accordance with GAAP because Billtrust is unable to provide this reconciliation without unreasonable effort due to the uncertainty and inherent difficulty of predicting the anticipated expense related to such projections, which is variable. You should review Billtrust’s audited financial statements, which will be included in the registration statement relating to the proposed business combination.IMPORTANT ADDITIONAL INFORMATION AND WHERE TO FIND ITThis communication is being made in respect of the proposed business combination involving South Mountain and Billtrust. South Mountain intends to file a registration statement on Form S-4 with the SEC, which will include a proxy statement of South Mountain, a consent solicitation statement of Billtrust and a prospectus of South Mountain, and South Mountain will file other documents regarding the proposed Transactions with the SEC. A definitive proxy statement/consent solicitation statement/prospectus will also be sent to the stockholders of South Mountain and Billtrust, seeking any required stockholder approval. Before making any voting or investment decision, investors and security holders of South Mountain and Billtrust are urged to carefully read the entire registration statement and proxy statement/consent solicitation statement/ prospectus, when they become available, and any other relevant documents filed with the SEC, as well as any amendments or supplements to these documents, because they will contain important information about the proposed Transactions. The documents filed by South Mountain with the SEC may be obtained free of charge at the SEC’s website at www.sec.gov. In addition, the documents filed by South Mountain may be obtained free of charge from South Mountain at www.SMMergerCorp. Alternatively, these documents, when available, can be obtained free of charge from South Mountain upon written request to South Mountain Merger Corp., 767 Fifth Avenue, 9th Floor, New York, New York 10153, Attn: Secretary, or by calling (646) 446-2700.South Mountain, Billtrust and certain of their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from the stockholders of South Mountain, in favor of the approval of the Transactions. Information regarding South Mountain’s directors and executive officers is contained in South Mountain’s Annual Report on Form 10-K for the year ended December 31, 2019, which was filed with the SEC on March 20, 2020, and its Current Report on Form 8-K, which was filed with the SEC on June 29, 2020. Additional information regarding the interests of those participants, the directors and executive officers of Billtrust and other persons who may be deemed participants in the Transactions may be obtained by reading the registration statement and the proxy statement/consent solicitation statement/prospectus and other relevant documents filed with the SEC when they become available. Free copies of these documents may be obtained as described in the preceding paragraph.No Offer or Solicitation This presentation does not constitute an offer to sell or the solicitation of an offer to buy any securities, or a solicitation of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. Trademarks This presentation contains trademarks, service marks, trade names and copyrights of Billtrust, South Mountain and other companies, which are the property of their respective owners. 

   South Mountain overview  SMMC Management Team Led CardConnect to SuccessReturns Since FinTech Acquisition Corp Announced the Acquisition of CardConnect    +~85% Total Return  CCN Outperformed the S&P 500 by +30% over ~1 year  (1)  Who we are and what we offer   CardConnect stock price performance  Indexed Share Price Performance  ¹ Stock price appreciation from 03/07/2016 merger announcement to First Data’s offer price of $15/share2 Warrant price appreciation from 03/07/2016 merger announcement to First Data’s acquisition. Assumes $3.90 acquisition warrant price  (2)  Extensive public company experience at CardConnect and First Data  Anchor investors and significant portion of committed capital from long-term investors  Execution and structuring capability within the Financial Technology sector  $250mm equity capitalraised in June 2019via a listing on the Nasdaq  Strong track record of identifying and sourcing transactions with proven playbook of value creation  Proprietary sourcing channels and leadingindustry relationships with strategic corporates and financial sponsors 

 Billtrust at a glance     Transaction summary  Billtrust team  Flint Lane Founder & CEO  Steve PinadoPresident  Mark ShifkeCFO  South Mountain Merger Corp. team  Chuck BernickerCEO, President, Director  Nick DermatasCFO  Transactions Details  Valuation  Capital Structure  Anticipated Timing  Overview  South Mountain Merger Corp. (NASDAQ: SMMC.U) is a publicly-listed special purpose acquisition company with $250mm in cash$200mm PIPE is being raised in support of the transaction   $200mm of pro forma cash held on the balance sheet  Pro forma enterprise value of $1,293mm, which equates to 10.5x 2021E revenue of $123mm  Transaction announcement October 19th and closing after SEC review process and receipt of approval by stockholders of SMMC and Billtrust  Ownership  68% existing shareholders; 19% SPAC IPO and founder shares; 13% PIPE investors  Closing CashConditions  $225mm of which $200mm has been committed via the PIPE and an incremental $22mm has been committed in the form of a non-redemption commitment from an institutional shareholder 

   Billtrust at a glance   1,800+Customers  $1 trillion+Invoice dollars processed  $49 billion+Total payment volume  $105 million2020E Net revenue  19%2020-2022E Net revenue CAGR   ~93%2019 Net recurring revenue percentage  100%+Net dollar retention  69%2020E Adjustedgross margin  Note: Data as of LTM 06/30/2020; All financial metrics presented here, including net revenue, net recurring revenue percentage, net revenue CAGR and adjusted gross margin, are presented on a non-GAAP basis. See the Appendix to this presentation for a reconciliation to the GAAP equivalent measure. The historical financial information presented is preliminary and subject to adjustment as Billtrust is in the process of completing its audit procedures for prior periods.1 This calculation aggregates data elements across our modules that may not be unique  We are a leader in the digital transformation of accounts receivable and the future of B2B Payments  (1) 

 Founder-led, visionary management team  Flint Lane Founder & CEO  Steve PinadoPresident  Mark ShifkeCFO  Previous experience 

     Billtrust’s equity story  Huge TAM with strong tailwinds in B2B commerce and electronic billing and payments  Proprietary platform combining cloud-based software and integrated payments capabilities  Loyal customer base with high retention rates across diverse industry verticals  Extensive distribution network with tremendous opportunity to scale and monetize payments              Strong revenue growth with high revenue visibility and expanding margins  Founder-led and visionary management team  Comprehensive, end-to-end B2B commerce solutions across the value chain                             

 Huge market with strong tailwinds in B2B commerce and payments  280+ billionGlobal invoices(1)  $120+ trillionGlobal commercial payments(3)  22%+Mid-term growth inglobal B2B e-invoicing market(2)    50%+ of B2B payments are still made by paper check, but COVID-19 has accelerated the shift to digital   (4)                ¹ Billentis E-Invoicing / E-Billing Digitisation & Automation report, September 2019; Represents business (B2B/G2B) invoices 2 2019-2024 CAGR based on Technavio report, February 20203 Visa Investor Day presentation, February 20204 Mastercard Business Payments 2022 Report, 2018         

 Conventional AR/AP processes are outdated, inefficient, manual, and largely paper-based              Request line of credit  Order enablement  Present invoice  Apply funds and update ERP  Process application and provide credit  Place an order  Pay invoice  Collect outstanding payments    4      6    8      7    2    3      5    1                                                                                                                                           

 AR is ripe for digital transformation  PaymentsERPs have little to no Electronic Invoice Presentment and Payment (EIPP) capabilities  OrderingB2B ordering is complex with disparate needs across verticals  Cash AppOnce payments are received, applying cash is incredibly time consuming and expensive  CreditB2B companies sell on credit, and evaluating credit risk on an ongoing basis is difficult  CollectionsWhen customers don’t pay in a timely fashion, how do you follow up effectively?  InvoicingPaper invoicing is still widespread and customers struggle to convince their customers to move to electronic                                              Opportunity to drive efficiencies and monetize payments along the process 

 The status quo: massive manual lift and a myriad of legacy solutions to send invoices and process payments                                                                        SUPPLIER      ERP        BANK      BUYER      ERP    BANK      Payments  Email/Phone  Epayables  ACH  Credit card  Paper check                        Email / Online  Print  Fax  A/P Portal  Invoices 

 Powerful, proprietary technology platform combining cloud-based software and integrated payments capabilities                                                                    Payments  Invoices  Email/Phone  Epayables  ACH  Credit card  Paper check            Email / Online  Print  Fax  A/P Portal      SUPPLIER  BUYER          ERP  ERP                  BANK      BANK       

 The industry also needs a B2B payments platform to connect buyers and suppliers  What are these payments truly costing us?  Why are these customers paying late?  How will we processtheir remittances?  Should we participatein these programs?  “                            Ourcustomer                  “  “  “  “  “  “  “ 

   Billtrust Business Payments Network is the Venmo for B2B  Connected platform for suppliers, buyers, and financial institutions                  Complex financial / payment data and streamlined reconciliation                            Online directory with full view of participating suppliers and payment acceptance preferences          Suppliers receive homogenized remittance information to apply to their ERP system                                    Supplier ERP  Buyer ERP                  One billing file out from ERP  One paymentsfile into ERP  Business Payments Network (“BPN”)  Banks & AP systems                  Process starts over with next purchase    BPN              Powered by Billtrust 

   There is a new generation of companies focused on B2B automation  Focus  End market  Integrated payments  Total payment volume  Customers  Employees  AR automation  Enterprise / mid-market  Yes  AR / AP automation  SMBs  Yes  618  98,000+  $96bn+  $49bn+  1,800+  558  Procurement  Enterprise  Early days  1,693  1,400+  N/A  Note: Billtrust data as of LTM 06/30/2020; Bill.com and Coupa data as of latest company filings and investor presentations 

       Payment method  Remittance  Buyers  Suppliers                    Automated credit application, decisioning, and management  eCommerce marketplace with configurable web stores  Accept and manage payments and remittances in nearly any format  Reduce overdue receivables, bad debt, and write-offs  Comprehensive, end-to-end B2B commerce solutions across the value chain  Streamlined and simplified invoice delivery and presentment  Invoicing  Credit  Order  Collections  Payments  Cash App                                Payments  Payment acceptance flexibility  Multiple payment modalities  Embedded remittance  Process optimization  Financial ecosystem integrator / connector 

 Why we win in the market                  We deploy great software  We have extensive ecosystem integrations  Enabling frictionless money movement  Generating high customer ROI                                            Net dollar retention  100%+  NPS score  50+  AP integrations  160    Note: Data as of LTM 06/30/2020 

 Loyal customers across diverse industry verticals  Top 10 customers contribute ~18% of total net revenue  Tech  Construction  CPG  Industrial  Healthcare  4 of the 5 LargestIT distributors  4 of the 10 Largestmedical suppliers  6 of the 10Largest Less-than-truckload carriers  4 of the 10 Largest equipment dealers  8 of the 10 Largest building material suppliers  3 of the 10 Largest food distributors  Note: Data as of LTM 06/30/2020; net revenue is a non-GAAP measure (see Appendix for a reconciliation to the GAAP equivalent measures)                               

 Case studies      Results                              Problem                            Outdated ACH  Issue-prone online payment portal  Time consuming process  Low customer satisfaction    Reduction in daily cash application  20-hour  Match rate achieved for ACH  99.5%  Annual growth in electronic payments   20%+  Internal teams burdened by 760,000 mail invoices a month  Time consuming process  Manual process    ePresentment achieved  71%  Customers converted to eInvoicing in 1 year  33K  Invoices emailed per month  800K+    Global leader in performance‑driven golf products  Global storage and information management solutions provider 

 Billtrust go-to-market strategy  New logo  Mid-market  Enterprise  Existingcustomer  Large and growing market with whitespace opportunity  Disciplined sales and marketing approach  Cost effective customer acquisition strategy  Strong growth within existing customer base  MarketingBroad reach, campaign, and content-drivenSalesDirect, channel  MarketingTargeted ABMSalesDirect, channel  MarketingAccount coverage, targeted campaign and contentSalesDirect 

 Multiple avenues for future growth  Direct salesWin new logos and cross-sell / up-sell in the enterprise market  BusinessPayments NetworkScale the Business Payments Network and cross-sell other solutions  Channel distributionFurther penetrate the mid-market  New geographical marketsGlobal expansion                    Strategic M&AAcquire attractive, accretive businesses (new solutions, new verticals)                          Monetize paymentsIncrease volume of payments processed 

 $120T of B2B payments (1) between companies annually  $1T+ invoice dollars processed (2) and currently monetizing only $49bn+ (3) of payments  Overall payment volume is growing 36% year over year on Billtrust’s platform (3)                      1 Visa Investor Day presentation, February 20202 This calculation aggregates data elements across our modules that may not be unique3 Data as at LTM 06/30/2020  $120 trillion (1)  $49 billion+ (3)  $1 trillion+ (2)  Tremendous opportunity to monetize payments            Total payment volume  Invoice dollars processed(3)   Total payment volume 

 Business Payments Network by the numbers  -  LTM(2)   ~$170mm  $2bn+    Paymentsprocessed  ~70K  955K    Transactions processed  15+  234%  Network payablespartners  Revenue growth YoY(2)  2017    1 September 2020 annualized2 As of LTM 6/30/2020  Today(1)   $5bn+  ~1,600K 

 Opportunity to expand into large, new markets with compatible trends                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              280+ billionglobal invoicevolume(1)      International capabilities        Invoice delivery abroad    Multiplecurrencies        Multiplelanguages          Regulatorycompliance            ¹ Billentis E-Invoicing / E-Billing Digitisation & Automation report, September 2019; Represents business (B2B/G2B) invoices  

 How Billtrust makes money  Contracted recurring revenue for software generated from tiered subscription pricing models on evergreen contracts  SUBSCRIPTION  Per transaction recurring processing fees based on electronic bills delivered and bills/pages stored via our software platform, or the number of printed envelopes, on evergreen contracts  TRANSACTION INVOICING  Customers are charged a percentage of payment volume processed or per item processing fees at contracted rates based on number of payments, invoices paid, or files sent  TRANSACTION PAYMENTS  Professional fees generated from implementations and consulting   SERVICES                           

 Strong underlying operating metrics driving top-line growth  Number of eBills presented (mm)  Card payment volume ($mm)  15% CAGR  39% CAGR  37% CAGR  Total payment volume ($mm) 

 Rapid growth in Software and Payments revenue with high gross margins  Net revenue ($mm)  Adjusted gross profit ($mm)  CAGR  39%  (2%)  25%  69  80  96  21% CAGR  Adjusted gross margin  18% CAGR  67%  67%  64%    Print  Services and other  Software and Payments  1 Net revenue, adjusted gross profit, and adjusted gross margin are non-GAAP financial measures; see Appendix for a reconciliation to the GAAP equivalent measures. This information is preliminary and is subject to adjustment as Billtrust is in the process of completing its audit procedures for the periods presented.  (1) 

 Impact of COVID-19  YoY bill count ratio – 15 day moving average (existing customer cohort)(1)  >90% of total July net revenue   YoY invoice growth (July 2020)  Year over Year Ratio  YoY invoice growth by industry in July 2020      Swift Recovery  Covid Impact  Sept 29, 2020Ratio of 0.95  1.0  0.8  0.6  Mar 2020  Apr 2020  May 2020  Jun 2020  Jul 2020  Aug 2020  Sept 2020  Note: Net revenue is a non-GAAP measure (see Appendix for a reconciliation to the GAAP equivalent measures)1 Cohort includes 833 active customers who commenced billing prior to January 2019 and remained active as of March 2020   Building / Construction  Heavy equipment & machinery   

 Update on 1H 2020 financials  YoYgrowth  (12%)  16%  19%  18%  45  50  Adjusted gross margin  11%  69%  66%    Print  Services and other  Software and Payments  Net revenue ($mm)  Adjusted gross profit ($mm)  1 Net revenue, adjusted gross profit, and adjusted gross margin are non-GAAP financial measures; see Appendix for a reconciliation to the GAAP equivalent measures. This information is preliminary and is subject to adjustment as Billtrust is in the process of completing its review procedures for the periods presented.  (1) 

 Financial projections  CAGR  12%  (3%)  24%  105  123  148  Adjusted gross margin  19% CAGR    69%    70%  71%  Print  Services and other  Software and Payments  Net revenue ($mm)  Adjusted gross profit ($mm)  1 Net revenue, adjusted gross profit, and adjusted gross margin are non-GAAP financial measures. See Appendix for a reconciliation to the GAAP equivalent measures.  (1)   

       2017A revenue split  2022E revenue split  Print  Services and other  Software and Payments      Continued eAdoption from Print to EIPP      Monetizing BPN Opportunities      Monetizing Payment Opportunities        Estimated favorable shift in revenue mix going forward  2019A revenue split      Note: May not sum to 100% due to rounding. 1 This information is preliminary and is subject to adjustment as Billtrust is in the process of completing its audit procedures for the periods presented.  (1)  (1) 

 Long-term target operating model   Non-GAAP measures  Target % of revenue   Adjusted gross margin  80%+  S&M  25%  R&D  20%  G&A  10%  Adjusted EBITDA   25%+   Note: Non-GAAP financial figures exclude stock-based compensation expense and the amortization of acquired intangible assets. The company has not reconciled, any of the non-GAAP measures referenced above to the most comparable GAAP measure in its long-term target non-GAAP operating model because certain items are out of the company's control and/or cannot be reasonably predicted. Accordingly, a reconciliation is not available without unreasonable effort. 

 Transaction Overview 

 Transaction overview  Pro forma valuation ($mm, except per share data)  Pro forma ownership at close  Illustrative Sources ($mm)  Illustrative Uses ($mm)  1 Includes 6mm shares triggered at $12.50 per share and 6mm shares triggered at $15.00 per share for a total earn-out consideration of $165mm 2 Assumes no redemptions by SMMC’s existing shareholders3 Assumes 3.13mm founder shares at $10.00. Additional 0.94mm and 0.94mm founder shares subject to $12.50 and $15.00 earnouts, respectively     (1)     (2)     (3) 

 Attractive initial valuation relative to peers  Financial SaaS(2)  High-growth FinTech(2)  FV / 2021E revenue / 2021E growth  0.6x   1.4x   1.3x   0.9x   0.8x   2020E – 2022Erevenue CAGR  19%(1)   29%   27%   36%   24%   2021E grossmargin  70%(3)   74%   72%   42%   73%   Marketpositioning  Leader in AR automationProprietary platform with integrated paymentsLoyal enterprise customer base  Leader in AP automationSMB customer base  Procurement software solutionsEarly stages of integrated payments  Industry disruptorsMixed revenue models with volume and subscription components  Subscription revenue modelsCloud-based automated solutions  Source: Company materials; FactSet as of 11/10/2020¹ CAGR estimate based on net revenue (non-GAAP)2 Metrics reflect median of peer set3 Estimate based on adjusted gross margin, which is a non-GAAP measure 

     Billtrust’s equity story  Huge TAM with strong tailwinds in B2B commerce and electronic billing and payments  Proprietary platform combining cloud-based software and integrated payments capabilities  Diverse customer base with high retention rates across industry verticals  Extensive distribution network with tremendous opportunity to scale and monetize payments    Strong revenue growth with high revenue visibility and expanding margins  Founder-led and visionary management team  Comprehensive, end-to-end B2B commerce solutions across the value chain                                          Questions? 

   Appendix 

 Peer operating and trading metrics  Sorted by 2021E FV / Revenue  Primary  Source: FactSet as of 11/10/2020Note: FCF defined as CFO – Capex1 Represents pre-COVID market peak  High-growth FinTech  Financial SaaS  (1) 

 Definitions  Net revenue (non-GAAP) is defined as total revenues, less reimbursable costs revenue.Adjusted gross profit is defined as total revenues less total cost of revenues, excluding depreciation and amortization, plus stock based compensation expense included in total cost of revenues.Adjusted gross margin is defined as Adjusted gross profit divided by its total revenues less reimbursable costs revenue, or net revenue (non-GAAP).EBITDA is defined as Net loss and comprehensive loss, plus (i) provision (benefit) for income taxes, (ii) other expense (income), (iii) interest expense, (iv) depreciation and amortization. EBITDA margin is defined as EBITDA divided by net revenue (non-GAAP). Adjusted EBITDA is defined as Net loss and comprehensive loss, plus (i) provision (benefit) for income taxes, (ii) other expense (income), (iii) interest expense, (iv) depreciation and amortization, (v) stock based compensation expense, (vi) restructuring and severance costs, and (vii) acquisition and integration costs.Adjusted EBITDA margin is defined as Adjusted EBITDA divided by net revenue (non-GAAP). Free cash flow is defined as net cash used in operating activities less purchases of property and equipment, and less capitalization of internal-use software costs.Free cash flow margin is defined as free cash flow divided by net revenue (non-GAAP).Net recurring revenue percentage is defined as subscription and transaction fees divided by net revenue (non-GAAP).Net dollar retention rate is calculated by comparing, for a given period, actual recurring revenue (excluding revenue for expense reimbursements such as postage) for all customers who had recurring revenue for all three-months in the corresponding quarter of the prior year, to the same amount from the same customers in the given quarter. The calculation does not include new customers added during the one-year calculation period. This calculation includes additional modules purchased, pricing changes, transaction volume changes and product cancellations during the given period. For periods other than quarters, Billtrust takes the average of the quarters for the stated period. 

 Reconciliation of net revenue (non-GAAP) and adjusted gross margin  ($mm), year ending 12/31  2017A  2018A  2019A  2017A-2019A CAGR  2020E  2021E  2022E  2020-2022E CAGR                    Total Revenues  110  121  136  11%  142  161  183  13%  Less: Reimbursable costs revenue  (41)  (41)  (40)    (37)  (37)  (35)    Net revenue (non-GAAP)  69   80   96   18%  105   123   148   19%                     Adjusted Gross Profit  44   53   65     73   87   106     Gross margin excluding depreciation and amortization (%)  39%  44%  47%    51%  54%  58%    Adjusted gross margin (%) (1)  64%   67%   67%     69%   70%   71%     1 The historical information for 2017, 2018, 2019, 1H 2019, and 1H 2020 is preliminary and is subject to adjustment as Billtrust is in the process of completing the audit procedures for the periods presented.   (1)  ($mm), six months ending 6/30  1H 2019  1H 2020  YoY Growth          Total Revenues  $65   $69   5%  Less: Reimbursable costs revenue  ($20)  ($19)    Net revenue (non-GAAP)  $45   $50   11%          Adjusted Gross Profit  $30   $35     Gross margin excluding depreciation and amortization (%)  45%  50%    Adjusted gross margin (%) (1)  66%  69%   

 Reconciliation of non-GAAP net recurring revenue percentage  ($mm), year ending 12/31  2019A      Subscription and transaction fees  $89  Services and other  7  Reimbursable costs revenue  40  Total Revenues  136   Less: Reimbursable costs revenue   40  Net Revenue (non-GAAP)  96      Net recurring revenue percentage (1) (2)  93%   GAAP recurring revenue percentage (1) (3)  65%  1 The historical information for 2019 is preliminary and is subject to adjustment as Billtrust is in the process of completing the audit procedures for the periods presented.2 Net recurring revenue percentage is calculated as subscription and transaction fees divided by net revenue (non-GAAP).3 GAAP recurring revenue percentage is calculated as subscription and transaction fees divided by total revenues.   (1) 

 Reconciliation of historical non-GAAP financial metrics  ($mm), year ending 12/31  2017A  2018A  2019A          Net loss and comprehensive loss  (17)  (18)  (23)  Add: Depreciation and Amortization  5   6   6  Add: Other expense (Income)  1   1   2   Add: Income Expense/(Tax Benefit)  (1)  0   0   EBITDA  (12)  (11)  (15)          Net loss and comprehensive loss  (17)  (18)  (23)  Add: Depreciation and Amortization  5   6   6   Add: Other Expense/(Income)  1   1   2  Add: Income Expense/(Tax Benefit)  (1)  0   0   Add: Stock based compensation expense  2   2   2   Add: Restructuring and severance  0   1   1   Add: Acquisition and Integration Costs  1   0   1   Adjusted EBITDA  (10)  (8)  (11)          Net cash used in operating activities  (6)  (6)  (7)  Less: Purchases of property  (2)  (7)  (3)  Less: Capitalization of internal-use software costs  (0)  (1)  (1)  Free Cash Flow  (8)  (14)  (12)  1 The historical information for 2017, 2018 and 2019 is preliminary and is subject to adjustment as Billtrust is in the process of completing the audit procedures for the periods presented.  (1) 

 Summary financials  ($mm), year ending 12/31  2017A  2018A  2019A  2020E  2021E  2022E                Software and Payments  44   54   69   80   97   123   % growth    23%   28%   16%   21%   26%   Print  21   21   21   19   19   17   % growth    (1%)  (2%)  (10%)  (0%)  (6%)  Services and Other  4   5   7   6   8   8   % growth    28%   50%   (8%)  20%   5%   Net Revenue (non-GAAP)  69   80   96   105   123   148   % growth    16%   21%   9%   18%   20%                  Adjusted Gross Profit  44   53   65   73   87   106   % Adjusted gross margin  64%   67%   67%   69%   70%   71%                  Research & Development  (20)  (24)  (34)        Sales & Marketing  (21)  (22)  (22)        General & Administrative  (16)  (19)  (23)        Total Operating Expenses  (56)   (64)  (80)                          EBITDA  (12)  (11)  (15)           % margin  (18%)  (14%)  (15%)                       Adjusted EBITDA  (10)  (8)  (11)           % margin  (14%)  (10%)  (12%)                      Free Cash Flow  (8)  (14)  (12)                      1 The historical information for 2017, 2018 and 2019 is preliminary and is subject to adjustment as Billtrust is in the process of completing the audit procedures for the periods presented.  (1)