13D Filing: Siris Capital Group, LLC and Synchronoss Technologies Inc (SNCR)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

SYNCHRONOSS
TECHNOLOGIES, INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

87157B103

(CUSIP Number)

Steven Spencer

Siris Capital Group, LLC

601 Lexington Avenue, 59th Floor

New York, NY 10022

(212)-231-0095

(Name,
Address and Telephone Number of Person Authorized to Receive Notices and Communications)

April 28, 2017

(Date of Event Which Requires Filing of This Statement)

  If
the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box.  ☐

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for
other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall
not be deemed to be filed for the purpose of section 18 of the Securities Exchange Act of 1934 (Act) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act
(however, see the Notes).

This statement on Schedule 13D (this Schedule 13D) relates to
the common stock, $0.0001 par value per share (the Common Stock), of Synchronoss Technologies, Inc., a Delaware corporation (the Company). The principal executive offices of the Company are located at 200
Crossing Boulevard, 8th Floor, Bridgewater, New Jersey 08807. As reported in the Companys proxy statement filed with the Securities and Exchange Commission (the Commission) on April 6, 2017, as of March 27, 2017,
there were 46,372,470 shares of Common Stock outstanding.

(a) This Schedule 13D is being filed jointly on behalf of the following persons
(collectively, the Reporting Persons):

Silver Holdings is controlled by its sole member, Silver Parent. Silver Parent is controlled by its members, Siris Fund III and Siris Fund III Parallel. Each
of Siris Fund III and Siris Fund III Parallel is controlled by its general partner, Siris Fund III GP. Siris Fund III GP is controlled by its general partner, Siris Fund III GP HoldCo. Siris Fund III Advisor serves as investment manager to Siris
Fund III and Siris Fund III Parallel pursuant to investment management agreements with each of them. Siris Capital Group shares investment management authority in respect of Siris Fund III and Siris Fund III Parallel pursuant to an agreement between
Siris Fund III Advisor and Siris Capital Group. Siris Fund III Advisor is controlled by its general partner, Siris Fund III Advisor HoldCo. Siris Capital Group is controlled by its managing member, Siris Advisor HoldCo. Each of Siris Fund III GP
HoldCo, Siris Fund III Advisor HoldCo and Siris Advisor HoldCo is controlled by Frank Baker, Peter Berger and Jeffrey Hendren, each a United States citizen. The agreement among the Reporting Persons relating to the joint filing of this Schedule 13D
is attached to this Schedule 13D as Exhibit 99.1.

(b) The business address of each of the persons listed in this Item 2 is c/o Siris Capital Group,
LLC, 601 Lexington Avenue, 59th Floor, New York, NY 10022.

(c) The principal business of Silver Holdings is to invest from time to time in the securities
of the Company. The principal business of Silver Parent is to serve as the sole member of Silver Parent. Siris Fund III and Siris Fund III Parallel are private equity funds, the principal business of which is to make investments. The principal
business of Siris Fund III GP is to serve as the general partner of Siris Fund III and Siris Fund III Parallel and related investment vehicles. The principal business of Siris Fund III GP HoldCo is to serve as the general partner of Siris Fund III
GP. The principal business of Siris Fund III Advisor is to serve as the investment manager of Siris Fund III and Siris Fund III Parallel. The principal business of Siris Fund III Advisor HoldCo is to serve as the general partner of Siris

Fund III Advisor. The principal business of Siris Capital Group is to provide investment management and related services to affiliated investment funds or similar vehicles, including Siris Fund
III and Siris Fund III Parallel. The principal business of Siris Advisor HoldCo is to serve as the managing member of Siris Capital Group. The present principal occupation or employment of each of Messrs. Baker, Berger and Hendren is to serve as a
Managing Partner of Siris Capital Group and related entities.

(d) During the last five years, none of the persons listed in this Item 2 has been
convicted in any criminal proceeding (excluding traffic violations or similar misdemeanors).

(e) During the last five years, none of the persons listed
in this Item 2 has been party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting
or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

(f) The citizenship of each of
the persons listed in this Item 2 is set forth in (a) above.

The 5,994,667 shares of Common Stock reported herein
(the Shares) were purchased by Silver Holdings for an aggregate purchase price of $86,894,494.08 (excluding brokerage commissions). The funds for such purchases were provided to Silver Private Holdings I, LLC by Siris Partners III
and Siris Partners III Parallel, which obtained such funds from capital contributions by their respective partners and borrowings under a short term loan facility with Macquarie Capital Funding LLC.

Siris Capital Group has followed the Company for several years and, between
April 27, 2017 and May 4, 2017, the Reporting Persons acquired the Shares for investment purposes, mindful that they may be interested in pursuing a potential strategic transaction involving the Company.

On the evening of May 4, 2017, Frank Baker, a managing partner of Siris Capital Group, met with Stephen Waldis, CEO, Founder and Executive Chairman of
the Board of the Company. At the meeting, Mr. Baker informed Mr. Waldis of the Reporting Persons beneficial ownership of the Shares, and expressed the Reporting Persons interest in discussing with the Board of Directors (the
Board) of the Company one or more potential strategic transactions (each a Potential Transaction), which may include a take-private, a significant minority investment or other strategic transaction. Mr. Baker
also discussed with Mr. Waldis the subject matter of a letter (the May 4 Letter) that the Reporting Persons were prepared to provide to the Board. A copy of the May 4 Letter is attached hereto as Exhibit 99.2 and incorporated
herein by reference. Subsequent to the meeting, Mr. Baker delivered the May 4 Letter to Mr. Waldis.

Consistent with their investment policies, the
Reporting Persons intend to review and evaluate their investment in the Company on a continuing basis. They may communicate with the Board, Company management, other shareholders of the Company, lenders to the Company and/or other relevant parties
from time to time with respect to operational, strategic, financial or governance matters of the Company, including a Potential Transaction, or otherwise seek to work constructively with the Company. Depending on various factors, including the
results of any such discussions, the Reporting Persons may in the future take such actions with respect to their investment in the Company as they deem appropriate, including: pursuing a Potential Transaction, purchasing additional shares of Common
Stock or other Company securities (which may include rights or securities exercisable for or convertible into securities of the Company) or selling some or all of their Shares (which may include transferring some or all of such securities to
affiliates or distributing some or all of such securities to partners, members or beneficiaries, as applicable); engaging in any hedging or other derivative transactions with respect to the Common Stock; taking positions or making proposals with
respect to, or taking other actions to effect changes in, the strategy, board or management composition, or ownership structure, of the Company; encouraging the Company to pursue one or more strategic transactions; and/or otherwise changing their
intention with respect to any and all matters referred to in Item 4 of Schedule 13D. Any such steps that the Reporting Persons may pursue may be taken at any time and from time to time without prior notice and will depend on a variety of factors,
including the price and availability of the Companys securities, subsequent developments affecting the Company, the Companys business and prospects, other investment and business opportunities available to the Reporting Persons, general
industry and economic conditions, the securities markets in general, tax considerations, applicable law and other factors deemed relevant by the Reporting Persons.

There can be no assurance as to the outcome of any of the discussions referred to in this Schedule 13D, including
whether such discussions will occur, whether a Potential Transaction will be agreed between the parties, or any of the terms, structure or timing of any such Potential Transaction.

Other than as described in this Item 4, or as would occur upon completion of any of the matters discussed herein, none of the Reporting Persons has any
current plans or proposals that relate to or that would result in any of the transactions or other matters specified in clauses (a) through (j) of Item 4 of Schedule 13D; provided, that the Reporting Persons, at any time and from time to time,
may review or reconsider and change their positions and/or intentions.

(a)-(b) The aggregate number and percentage of shares of Common
Stock of the Company to which this Schedule 13D relates is 5,994,667 shares, constituting approximately 12.93% of the Companys outstanding shares of Common Stock. This percentage is based on an aggregate of 46,372,470 shares of Common Stock
outstanding as of March 27, 2017, as provided by the Company in its proxy statement filed with the Commission on April 6, 2017. All of the Shares are held by Silver Holdings. None of the other Reporting Persons holds any shares of Common
Stock.

The Reporting Persons may be deemed to be members of a group for purposes of Section 13(d) of the Securities Exchange Act of 1934, as
amended, and the rules and regulations thereunder, which group may be deemed to share the power to vote or direct the vote, or to dispose or direct the disposition, of the Shares. However, neither the filing of this Schedule 13D nor any of its
contents shall be deemed to constitute an admission by any of the Reporting Persons that it is a member of a group for such purposes or for any other purpose. Each of the Reporting Persons expressly disclaims beneficial ownership of
securities held by any other person or entity other than, to the extent of any pecuniary interest therein, the various accounts under such Reporting Persons management and control.

(c) Schedule I hereto, which is incorporated herein by reference, sets forth the transactions in the Common Stock that were effected in the past 60 days by
the Reporting Persons. All of such transactions were effected in open market transactions.

(d) No person other than the Reporting Persons is known to the
Reporting Persons to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares.

(e)
Not applicable.

Except as described herein, the Reporting Persons have no contracts, arrangements, understandings or relationships (legal or otherwise) with respect to any
securities of the Company.

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, the undersigned certifies that the information set forth in this
statement is true, complete and correct.

Dated: May 5, 2017

SCHEDULE I

TRADING IN SHARES

Between April 27,
2017 and May 4, 2017, the Reporting Persons made the following transactions in the Common Stock. The Reporting Persons undertake to provide, upon request by the Commission, full information regarding the number of shares of Common Stock
purchased at each separate price for these transactions.