X0306 4/A 2021-05-14 2021-05-18 0001610950 Syneos Health, Inc. SYNH 0001260943 THOMAS H. LEE ADVISORS, LLC C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001775519 Thomas H. Lee Equity Fund VI (2019), L.P. C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET BOSTON MA 02110 true 0001260945 THOMAS H LEE PARTNERS LP 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001780726 THL Fund VI (2019) Coinvestment Partners, L.P. C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001620946 Thomas H. Lee Equity Fund VII, L.P. C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001620947 Thomas H. Lee Parallel Fund VII, L.P. C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001620948 Thomas H. Lee Parallel (Cayman) Fund VII, L.P. C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001604098 THL Managers VI, LLC C/O THOMAS H. LEE PARNTERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001753032 THL Managers VII, LLC C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true 0001757181 THL HOLDCO, LLC C/O THOMAS H. LEE PARTNERS, L.P. 100 FEDERAL STREET, 35TH FLOOR BOSTON MA 02110 true Class A Common Stock 2021-05-12 4 S 0 379789 81.04 D 5208871 I See footnote Class A Common Stock 2021-05-12 4 S 0 64 81.04 D 852 D Class A Common Stock 2021-05-12 4 S 0 25 81.04 D 327 D See Exhibit 99.1 for text of footnote (1). See Exhibit 99.1 for text of footnote (2). See Exhibit 99.1 for text of footnote (3). See Exhibit 99.1 for text of footnote (4). See Exhibit 99.1 for text of footnote (5). See Exhibit 99.1 for text of footnote (6). See Exhibit 99.1 for text of footnote (7). See Exhibit 99.1 for text of footnote (8). See Exhibit 99.1 for text of footnote (9). See Exhibit 99.1 for text of footnote (10). Exhibit 99.1 (Form 4 Footnotes) and Exhibit 99.2 (Joint Filer Information) are incorporated herein by reference. This Form 4 is the first of two Forms 4 being filed relating to the same event. The Form 4 has been split into two filings because there are more than 10 Reporting Persons in total, and the SEC's EDGAR filing system limits a single Form 4 to a maximum of 10 Reporting Persons. Each Form 4 will be filed by Designated Filer Thomas H. Lee Advisors, LLC. This amendment to Form 4 is being filed solely to (i) correct the number of shares reflected as being held by Fund VI 2019 following the closing of the Overallotment Option and the number of shares reflected as being distributed by Fund VI 2019 in footnote 6 to the Form 4 filed on March 18, 2021 (the "Original Form 4"), from 1,449,400 shares to 1,449,436 shares, and 12,806 shares to 12,770 shares, respectively, and (ii) correct the aggregate number of shares reflected as being held by the THL Funds as disclosed in Table I of the Original Form 4, from 5,208,835 shares to 5,208,871 shares. ** See Exhibit 99.2 for Signatures 2021-05-20