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Iqvia Holdings Inc. – ‘10-Q’ for 3/31/21 – ‘EX-101.DEF’

On:  Friday, 4/23/21, at 4:12pm ET   ·   For:  3/31/21   ·   Accession #:  1478242-21-43   ·   File #:  1-35907

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  As Of               Filer                 Filing    For·On·As Docs:Size

 4/23/21  Iqvia Holdings Inc.               10-Q        3/31/21   75:6.1M

Quarterly Report   —   Form 10-Q
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-Q        Quarterly Report                                    HTML    680K 
 2: EX-31.1     Certification -- §302 - SOA'02                      HTML     27K 
 3: EX-31.2     Certification -- §302 - SOA'02                      HTML     27K 
 4: EX-32.1     Certification -- §906 - SOA'02                      HTML     25K 
 5: EX-32.2     Certification -- §906 - SOA'02                      HTML     25K 
12: R1          Cover Page                                          HTML     75K 
13: R2          Condensed Consolidated Statements of Income         HTML    104K 
14: R3          Condensed Consolidated Statements of Comprehensive  HTML     54K 
                Income (Loss)                                                    
15: R4          Condensed Consolidated Statements of Comprehensive  HTML     30K 
                Income (Loss) (Parenthetical)                                    
16: R5          Condensed Consolidated Balance Sheets               HTML    133K 
17: R6          Condensed Consolidated Balance Sheets               HTML     33K 
                (Parenthetical)                                                  
18: R7          Condensed Consolidated Statements of Cash Flows     HTML    105K 
19: R8          Condensed Consolidated Statements of Stockholders'  HTML     79K 
                Equity                                                           
20: R9          Summary of Significant Accounting Policies          HTML     29K 
21: R10         Revenues by Geography, Concentration of Credit      HTML     57K 
                Risk and Remaining Performance Obligations                       
22: R11         Trade Accounts Receivable, Unbilled Services and    HTML     41K 
                Unearned Income                                                  
23: R12         Goodwill                                            HTML     36K 
24: R13         Derivatives                                         HTML     53K 
25: R14         Fair Value Measurements                             HTML     59K 
26: R15         Credit Arrangements                                 HTML     64K 
27: R16         Stockholders' Equity                                HTML     26K 
28: R17         Restructuring                                       HTML     36K 
29: R18         Income Taxes                                        HTML     26K 
30: R19         Comprehensive Income (Loss)                         HTML     54K 
31: R20         Segments                                            HTML     60K 
32: R21         Earnings Per Share                                  HTML     31K 
33: R22         Subsequent Events                                   HTML     25K 
34: R23         Summary of Significant Accounting Policies          HTML     30K 
                (Policies)                                                       
35: R24         Revenues by Geography, Concentration of Credit      HTML     50K 
                Risk and Remaining Performance Obligations                       
                (Tables)                                                         
36: R25         Trade Accounts Receivable, Unbilled Services and    HTML     42K 
                Unearned Income (Tables)                                         
37: R26         Goodwill (Tables)                                   HTML     36K 
38: R27         Derivatives (Tables)                                HTML     55K 
39: R28         Fair Value Measurements (Tables)                    HTML     55K 
40: R29         Credit Arrangements (Tables)                        HTML     66K 
41: R30         Restructuring (Tables)                              HTML     36K 
42: R31         Comprehensive Income (Loss) (Tables)                HTML     56K 
43: R32         Segments (Tables)                                   HTML     55K 
44: R33         Earnings Per Share (Tables)                         HTML     31K 
45: R34         Summary of Significant Accounting Policies -        HTML     27K 
                Additional Information (Detail)                                  
46: R35         Revenues by Geography, Concentration of Credit      HTML     50K 
                Risk and Remaining Performance Obligations -                     
                Summary of Revenues by Geographic Region and                     
                Reportable Segment (Detail)                                      
47: R36         Revenues by Geography, Concentration of Credit      HTML     24K 
                Risk and Remaining Performance Obligations -                     
                Additional Information (Detail)                                  
48: R37         Revenues by Geography, Concentration of Credit      HTML     31K 
                Risk and Remaining Performance Obligations -                     
                Future Obligation Terms (Detail)                                 
49: R38         Trade Accounts Receivable, Unbilled Services and    HTML     35K 
                Unearned Income - Trade Accounts Receivable and                  
                Unbilled Services (Detail)                                       
50: R39         Trade Accounts Receivable, Unbilled Services and    HTML     38K 
                Unearned Income - Schedule of Net Contract Assets                
                (Liabilities) (Detail)                                           
51: R40         Trade Accounts Receivable, Unbilled Services and    HTML     31K 
                Unearned Income - Additional Information (Detail)                
52: R41         Goodwill - Summary of Goodwill by Reportable        HTML     38K 
                Segment (Detail)                                                 
53: R42         Derivatives - Summary of Fair Values of Derivative  HTML     44K 
                Instruments Designated as Hedges (Detail)                        
54: R43         Derivatives - Effect of Cash Flow Hedging           HTML     31K 
                Instruments on Other Comprehensive (Loss) Income                 
                (Detail)                                                         
55: R44         Derivatives - Additional Information (Detail)       HTML     24K 
56: R45         Fair Value Measurements - Additional Information    HTML     28K 
                (Detail)                                                         
57: R46         Fair Value Measurements - Fair Value of Financial   HTML     54K 
                Assets and Liabilities Measured on Recurring Basis               
                (Detail)                                                         
58: R47         Fair Value Measurements - Changes in Level 3        HTML     33K 
                Financial Assets and Liabilities Measured on                     
                Recurring Basis (Detail)                                         
59: R48         Credit Arrangements - Summary of Credit Facilities  HTML     44K 
                (Detail)                                                         
60: R49         Credit Arrangements - Summary of Debt (Detail)      HTML     89K 
61: R50         Credit Arrangements - Contractual Maturities of     HTML     40K 
                Long-term Debt (Detail)                                          
62: R51         Credit Arrangements - Additional Information        HTML     59K 
                (Detail)                                                         
63: R52         Stockholders' Equity - Narratives (Detail)          HTML     43K 
64: R53         Restructuring - Summary of Amounts Recorded for     HTML     38K 
                Restructuring Plans (Detail)                                     
65: R54         Income Taxes - Narratives (Detail)                  HTML     29K 
66: R55         Comprehensive Income (Loss) - Summary of            HTML     53K 
                Components of AOCI (Detail)                                      
67: R56         Comprehensive Income (Loss) - Summary of            HTML     40K 
                Adjustments for (Gains) Losses Reclassified from                 
                AOCI into Condensed Consolidated Statements of                   
                Income and Affected Financial Statement Line Item                
                (Detail)                                                         
68: R57         Segments - Additional Information (Detail)          HTML     24K 
69: R58         Segments - Operations by Reportable Segments        HTML     61K 
                (Detail)                                                         
70: R59         Earnings Per Share - Summary of Weighted-Average    HTML     30K 
                Outstanding Stock-Based Awards Excluded from                     
                Computation of Diluted Earnings Per Share (Detail)               
71: R60         Subsequent Events (Details)                         HTML     32K 
73: XML         IDEA XML File -- Filing Summary                      XML    136K 
11: XML         XBRL Instance -- iqv-20210331_htm                    XML   1.48M 
72: EXCEL       IDEA Workbook of Financial Reports                  XLSX     73K 
 7: EX-101.CAL  XBRL Calculations -- iqv-20210331_cal                XML    212K 
 8: EX-101.DEF  XBRL Definitions -- iqv-20210331_def                 XML    476K 
 9: EX-101.LAB  XBRL Labels -- iqv-20210331_lab                      XML   1.33M 
10: EX-101.PRE  XBRL Presentations -- iqv-20210331_pre               XML    768K 
 6: EX-101.SCH  XBRL Schema -- iqv-20210331                          XSD    139K 
74: JSON        XBRL Instance as JSON Data -- MetaLinks              329±   481K 
75: ZIP         XBRL Zipped Folder -- 0001478242-21-000043-xbrl      Zip    233K 


‘EX-101.DEF’   —   XBRL Definitions — iqv-20210331_def


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2 Previous Filings that this Filing References

  As Of               Filer                 Filing    For·On·As Docs:Size             Issuer                      Filing Agent

 4/16/21  IQVIA Holdings Inc.               8-K:5,9     4/13/21   13:247K
 3/03/21  IQVIA Holdings Inc.               8-K:1,2,9   3/03/21   13:1.3M
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