TREB Trebia Acquisition Corp

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Denotes less than 1%

Represents shares of System1 Class A Common Stock that the stockholders shown beneficially own as of January 27, 2022 or have the right to acquire within 60 days thereafter, upon vesting and exercise of stock options, upon exercise of warrants held by the stockholder or upon exercise of the stockholder’s redemption right of any

Assumes redemption of all Class B Units by all members of S1 Holdco for shares of System1 Class A Common Stock, which would have resulted in an additional 22,077,319 shares of System1 Class A Common Stock outstanding as of January 27, 2022. Includes shares that the stockholders shown have the right to acquire as of January 27, 2022 or within 60 days thereafter as described in immediately preceding footnote above.

Consists of (i) 35,000 warrants (the “Public Warrants”) exercisable for 35,000 shares of System1 Class A Common Stock at an exercise price of $11.50 per share held directly by Mr. Blend and (ii) 3,086,790 shares of System1 Class A Common Stock held by Lone Investment Holdings, LLC (“LIH”). Mr. Blend is the manager of LIH, and may be deemed to have voting and dispositive power over the shares held by LIH. Mr. Blend disclaims beneficial ownership in the shares held by LIH except to the extent of his pecuniary interest therein. Excludes (i) 172,440 shares of System1 Class A Common Stock and 961,613 shares of System1 Class A Common Stock issuable upon the exchange or redemption of 961,613 Class B Units of S1 Holdco (and cancellation of the corresponding Class C Common Stock, par value $0.0001 per share, of the Company (the “Class C Common Stock”) held by OpenMail2, LLC (“OpenMail2”) and (ii) 45,077 shares of System1 Class A Common Stock and 251,379 Class B Units of S1 Holdco (and the corresponding shares of Class C Common Stock of the Company), in each case, directly held by the Blend Family Foundation. OpenMail2 is jointly controlled by Michael Blend, Charles Ursini and Tridivesh Kidambi as members of the board of managers thereof and they may be deemed to jointly control the voting and dispositive power over the shares held by OpenMail2. The directors of the Blend Family Foundation are Michael Blend, Sandra Blend and Stanley Blend. The Public Warrants by their terms become exercisable (including by cash settlement) 30 days following the Closing Date. The terms of the Public Warrants are set forth in the Warrant Agreement filed with the SEC on June 22, 2020 as Exhibit 4.1 to the Company’s Current Report on Form 8-K. Holders of Class B Units of S1 Holdco are entitled to have their Class B Units of S1 Holdco exchanged or redeemed for System1 Class A Common Stock on a one-for-one basis or, at the election of the Company, a cash payment in an amount per Class B Unit of S1 Holdco redeemed and calculated based on the volume weighted average market price of a share of System1 Class A Common Stock at the time of redemption. The Class B Units of S1 Holdco do not have voting rights, but holders of Class B Units of S1 Holdco own a corresponding number of shares of Class C Common Stock of the Company, which have voting rights and vote together with the shares of System1 Class A Common Stock. Excludes 725,000 shares of System1 Class A Common Stock issuable upon the vesting of 725,000 RSUs that were granted to Mr. Blend as of the Closing Date of the Business Combination and vest upon the occurrence of: (a) the first trading day on which the volume weighted average price of System1 Class A Common Stock equals or exceeds $12.50 per share for any 20 trading days within a period of 30 consecutive trading days or (b) a Change of Control (as defined in the Business Combination Agreement) in which the valuation of System1 Class A Common Stock is equal to or in excess of $12.50 per share, in each case during the five-year period following the closing of the Business Combination.

Consists of (i) 15,000 Public Warrants exercisable for 15,000 shares of System1 Class A Common Stock at an exercise price of $11.50 per share held directly by Mr. Kidambi, (ii) 15,518 shares of System1 Class A Common Stock held by Mr. Kidambi’s spouse (who is also an employee of the Company) and (iii) 401,489 shares of System1 Class A Common Stock held directly by Mr. Kidambi. Excludes 172,440 shares of System1 Class A Common Stock and 961,613 shares of System1 Class A Common Stock issuable upon the exchange of 961,613 Class B Units of S1 Holdco (and cancellation of the corresponding shares of Class C Common Stock of the Company) held by OpenMail2. OpenMail2 is jointly controlled by Michael Blend, Charles Ursini and Tridivesh Kidambi as members of the board of managers thereof and they may be deemed to jointly control the voting and dispositive power over the shares held by OpenMail2.

Consists of (i) 3,737,205 shares of System1 Class A Common Stock directly held by Trasimene Trebia, LP (the “Trebia Sponsor”) and (ii) 4,734,167 shares of System1 Class A Common Stock issuable upon the exercise of 4,734,167 warrants directly held by the Trebia Sponsor. Excludes 833,750 shares of System1 Class A Common Stock issuable upon the automatic conversion of 833,750 shares of Class D Common Stock, par value $0.0001 per share, of the Company (the “Class D Common Stock”) held by the Trebia Sponsor. Under the Company’s Certificate of Incorporation, the Class D Common Stock is non-voting and does not

Consists of (i) 20,500 shares of System1 Class A Common Stock and 40,700 shares of System1 Class A Common Stock issuable upon exercise of 40,700 Public Warrants, in each case held directly by Mr. Kazerani, the spouse of Ms. Kazerani, and (ii) 12,000 shares of System1 Class A Common Stock held by Ms. Kazerani’s in-laws, over which shares Ms. Kazerani’s spouse has voting and dispositive power pursuant to a power of attorney granted to him.

Consists of (i) 500,000 shares of System1 Class A Common Stock issuable upon the exercise of 500,000 warrants (the “Private Placement Warrants”) originally issued in a private placement in connection with the initial public offering of Trebia and held by Just Develop It Limited (“JDIL”) and (ii) 28,650,499 shares of System1Class A Common Stock held by JDI & AFH Limited (“J&A”). Excludes 725,000 shares of System1Class A Common Stock granted to JDIL as of the Closing Date of the Business Combination and vest upon the occurrence of: (a) the first trading day on which the volume weighted average price of System1 Class A Common Stock equals or exceeds $12.50 per share for any 20 trading days within a period of 30 consecutive trading days or (b) a Change of Control (as defined in the related RSU grant notice and award agreement) in which the valuation of System1 Class A Common Stock is equal to or in excess of $12.50 per share, in each case during the five-year period following the closing of the Business Combination. The Private Placement Warrants by their terms become exercisable (including by cash settlement) 30 days following the Closing Date. The terms of the Private Placement Warrants are set forth in the Warrant Agreement filed with the SEC on June 22, 2020 as Exhibit 4.1 to the Company’s Current Report on Form 8-K.

Consists of 2,762,282 shares of System1 Class A Common Stock directly held by BGPT Trebia, LP (the “BGPT Sponsor”) and 2,499,167 shares of System1 Class A Common Stock issuable upon the exercise of 2,499,167 Warrants directly held by the BGPT Sponsor. Excludes 616,250 shares of System1 Class A Common Stock issuable upon the automatic conversion of 616,250 shares of Class D Common Stock held by the BGPT Sponsor. Under the Company’s Certificate of Incorporation, the Class D Common Stock is non-voting and does not confer economic rights other than the accrual of certain dividends, automatically converts into System1 Class A Common Stock on a one-for-one basis if, during the period beginning on the Closing Date and ending on the fifth anniversary of the Closing Date, either the volume-weighted average price of System1 Class A Common Stock equals or exceeds $12.50 per share for any 20 trading days within a period of 30 consecutive trading days or there is a “change in control” where the valuation of System1 Class A Common Stock equals or exceeds $12.50 per share (“Class D Conversion Event”), and is automatically forfeited to the Company for no consideration if a Class D Conversion Event has not occurred prior to the fifth anniversary of the Closing Date. The terms of the Class D Common Stock are set forth in the Certificate of Incorporation of the Company filed with the SEC as Exhibit 3.1 to this Current Report.

Consists of (i) 3,537,147 shares of System1 Class A Common Stock, 500,000 shares of System1 Class A Common Stock issuable upon the exercise of 500,000 warrants and 7,945,580 Class B Units of S1 Holdco (and the corresponding shares of Class C Common Stock of the Company), in each case, directly held by Lone Star Friends Trust (“Lone Star”), (ii) 592,514 shares of System1 Class A Common Stock and 251,379 Class B Units of S1 Holdco (and the corresponding shares of Class C Common Stock of the Company) directly held by the Dante Jacob Blend Trust, for which Mr. Blend is the trustee (the “Dante Trust”), (iv) 592,514 shares of System1 Class A Common Stock and 251,379 Class B Units of S1 Holdco (and the corresponding shares of Class C Common Stock of the Company) directly held by the Nola Delfina Blend Trust, for which Mr. Blend is the trustee (the “Nola Trust”), and (v) 45,367 shares directly held by Mr. Blend in his individual capacity. Mr. Blend is the trustee of each of Lone Star, the Dante Trust and the Nola Trust, and has voting and dispositive power over the shares held by each of Lone Star, the Dante Trust and the Nola Trust but disclaims beneficial interest in such shares except to the extent of any pecuniary interest therein (if any). Mr. Blend, an attorney at Clark

See Footnote (7) above.

Consists of 1,191,217 shares of System1 Class A Common Stock and 3,408,221 Class B Units of S1 Holdco (and the corresponding shares of Class C Common Stock of the Company), in each case, directly held by the CEE Holdings Trust. Jackson Hole Trust Co. is the trustee of the CEE Holdings Trust and has voting and dispositive power over the shares held by the CEE Holdings Trust but disclaims beneficial interest in such shares.