This Post-Effective Amendment No. 4 to Form S-4 on Form S-8 (this “Amendment”) to Vivint Smart Home, Inc.’s (the “Registrant”) Registration Statement on Form S-4 (File No. 333-233911) filed with the Securities and Exchange Commission (the “Commission”) on September 24, 2019, as amended by Amendment No. 1 filed with the Commission on October 29, 2019, Amendment No. 2 filed with the Commission on November 18, 2019, Amendment No. 3 filed with the Commission on November 25, 2019, Amendment No. 4 filed with the Commission on November 27, 2019, Amendment No. 5 filed with the Commission on December 2, 2019, Post- Effective Amendment No. 1 filed with the Commission on December 19, 2019, Post- Effective Amendment No. 2 filed with the Commission on December 23, 2019 and Post-Effective Amendment No. 3 filed with the Commission on March 24, 2020 (the “Form S-4” and, together with this Amendment, the “Registration Statement”), relates to the Class A common stock ( the “Common Stock”), $0.0001 par value per share of the Registrant. On January 17, 2020 (the “Closing Date”), the Registrant, consummated the previously announced merger pursuant to that certain Agreement and Plan of Merger, dated September 15, 2019, by and among the Registrant, Maiden Merger Sub, Inc., a subsidiary of the Registrant (“Merger Sub”), and Legacy Vivint Smart Home, Inc. (f/k/a Vivint Smart Home, Inc.) (“Legacy Vivint Smart Home”), as amended by Amendment No. 1 to the Agreement and Plan of Merger (the “Amendment” and as amended, the “Merger Agreement”), dated as of December 18, 2019, by and among the Registrant, Maiden Sub and Legacy Vivint Smart Home. Pursuant to the terms of the Merger Agreement, a business combination between the Registrant and Legacy Vivint Smart Home was effected through the merger of Merger Sub with and into Legacy Vivint Smart Home, with Legacy Vivint Smart Home surviving as the surviving company (the “Merger”). As of the effective time of the Merger (the “Effective Time”), each Company Group RSU (as defined in the Merger Agreement), to the extent then outstanding and unsettled, without any action on the part of the holder thereof, was automatically cancelled and converted into a restricted stock unit of the Registrant entitling the holder thereof to receive upon settlement a number of shares of Common Stock equal to the product of (x) the number of shares of Vivint Group, Inc. (“VGI”) common stock subject to such Company Group RSU as of immediately prior to the Effective Time, multiplied by (y) 0.0864152412 (the “VGI exchange ratio”), rounded down to the nearest whole number of shares of Common Stock (after such conversion, “Rollover RSUs”). As of the Effective Time, each Company Group SAR (as defined in the Merger Agreement) to the extent then outstanding and unexercised, without any action on the part of the holder thereof, was automatically cancelled and converted into a stock appreciation right of the Registrant with respect to a number of shares of Common Stock equal to the product of (x) the number of shares of VGI common stock subject to such Company Group SAR as of immediately prior to the Effective Time, multiplied by (y) the VGI exchange ratio, rounded down to the nearest whole number of shares of Common Stock, with a strike price per share of Common Stock equal to the quotient obtained by dividing (i) the per share strike price of such Company Group SAR as of immediately prior to the Effective Time by (ii) the VGI exchange ratio, rounded up to the nearest whole cent (after such conversion, “Rollover SARs”). As of the Effective Time, the Registrant assumed the Company Group LTIP Plans (as defined in the Merger Agreement), including any liabilities and obligations associated therewith and amended the Company Group LTIP Plans such that awards under the Company Group LTIP Plans will be settled in a number of shares of Common Stock with a fair market value equal to a number of hypothetical Rollover SARs with respect to (a) the number of shares of VGI common stock subject to the hypothetical Company Group SARs underlying such Company Group LTIP Plan as of immediately prior to the Effective Time, multiplied by (b) the VGI exchange ratio, rounded down to the nearest whole number of shares of Common Stock, with a strike price per share of Common Stock equal to the quotient obtained by dividing (x) the per share strike price of such hypothetical Company Group SARs as of immediately prior to the Effective Time by (y) the VGI exchange ratio, rounded up to the nearest whole cent (such assumed and amended plans, the “Rollover LTIP Plans”) as if the consummation of the Merger constituted an event similar to a “Public Offering” for purposes of the Company Group LTIP Plans. As of the Effective Time, each share of Company Restricted Stock (as defined in the Merger Agreement) was automatically, without any action on the part of the holder thereof, cancelled and converted into a number of shares of Common Stock equal to the VGI exchange ratio, rounded to the nearest whole share of Common Stock (after such conversion, “Rollover Restricted Stock” and together with the Rollover RSUs, the Rollover SARs and the hypothetical Rollover SARs under the Rollover LTIP Plans, the “Rollover Equity Awards”). The Rollover Equity Awards are subject to the Vivint Smart Home, Inc. 2020 Omnibus Incentive Plan, effective as of January 17, 2020 (as amended, the “Plan”) and to the same terms and conditions, including, without limitation, any vesting conditions (as modified pursuant to the terms of the Merger Agreement), as had applied to the corresponding Company Group Equity Award (as defined in the Merger Agreement) as of immediately prior to the Effective Time, except for such terms rendered inoperative by reason of the Merger, subject to such adjustments as reasonably determined by the Registrant’s board of directors to be necessary or appropriate to give effect to the conversion or the Merger. Holders of outstanding Rollover Equity Awards have the contingent right to receive earnout shares if, from the consummation of the Merger until the fifth anniversary thereof, the volume-weighted average price of Common Stock exceeds certain thresholds. The shares reserved for issuance in connection with the Rollover Equity Awards were previously registered on the Form S-4, but will now be subject to issuance pursuant to this Amendment.

Pursuant to Rule 416(a) under the Securities Act of 1933, as amended (the “Securities Act”), this Registration Statement also covers any additional shares of Common Stock that may become issuable in respect of the securities identified in the table above by reason of any stock dividend, stock split, recapitalization, merger, consolidation, reorganization, or other similar transaction which results in an increase in the number of outstanding shares of Common Stock.

All filing fees payable in connection with the registration of these securities were already paid in connection with the filing of the Form S-4, to which this is Post-Effective Amendment No. 4. Accordingly, no additional filing fee is required. See “Explanatory Note.”

Includes 9,735,701 shares previously registered pursuant to the Post-Effective Amendment No. 3 on Form S-8 to the Form S-4 filed with the Commission on March 24, 2020 (the “Post-Effective Amendment No. 3”) and 2,657,252 additional shares that were inadvertently omitted from the Post-Effective Amendment No. 3.