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

(Amendment No. 1)*

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)

May 19, 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 remainder of this cover page shall be filled out for a reporting persons initial filing on this form with respect to the subject class of securities, and for any subsequent amendment contain information which would alter disclosures provided in a prior cover page.

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).