Quest Diagnostics Incorporated
US ˙ NYSE ˙ US74834L1008

SecurityDGX / Quest Diagnostics Incorporated
InstitutionBoston Partners
Latest Disclosed Ownership4,012,232 shares
Latest Disclosed Value $ 786,652,146
Boston Partners reports 2.53% increase in ownership of DGX / Quest Diagnostics Incorporated

On May 11, 2026 - Boston Partners filed a 13F-HR form disclosing ownership of 4,012,232 shares of Quest Diagnostics Incorporated (US:DGX) valued at $786,317,227 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 3,913,326 shares of Quest Diagnostics Incorporated. This represents a change in shares of 2.53% during the quarter. The current value of the position is $777,048,971 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-11 2026-03-31 13F QUEST DIAGNOSTICS COM 74834L100 4,012,232 98,906 2.53 786,652 15.68 0.8240
2026-02-13 2025-12-31 13F QUEST DIAGNOSTICS COM 74834L100 3,913,326 -123,555 -3.06 680,020 -11.45 0.7041
2025-11-13 2025-09-30 13F QUEST DIAGNOSTICS COM 74834L100 4,036,881 997,033 32.80 767,978 40.83 0.7885
2025-08-12 2025-06-30 13F/A-1 QUEST DIAGNOSTICS COM 74834L100 3,039,848 744,102 32.41 545,318 40.28 0.6056
2025-08-07 2025-06-30 13F QUEST DIAGNOSTICS COM 74834L100 3,035,153 739,407 544,475 0.2500
2025-05-13 2025-03-31 13F QUEST DIAGNOSTICS COM 74834L100 2,295,746 2,295,746 388,724 0.4701
2020-05-13 2020-03-31 13F QUEST DIAGNOSTICS COM 74834L100 0 -1,987,056 -100.00 0 -100.00
2020-02-06 2019-12-31 13F/A-1 QUEST DIAGNOSTICS COM 74834L100 1,987,056 -1,597,507 -44.57 212,176 -44.67 0.2806
2020-02-05 2019-12-31 13F QUEST DIAGNOSTICS COM 74834L100 1,987,056 -1,597,507 212,176 119,291.5442
2019-11-20 2019-09-30 13F/A-1 QUEST DIAGNOSTICS COM 74834L100 3,584,563 -179,215 -4.76 383,470 0.08 0.5193
2019-11-08 2019-09-30 13F QUEST DIAGNOSTICS COM 74834L100 3,764,506 728 383,660 0.5074
2019-08-26 2019-06-30 13F/A-1 QUEST DIAGNOSTICS COM 74834L100 3,763,778 729,863 24.06 383,167 40.45 0.5025
2019-08-09 2019-06-30 13F QUEST DIAGNOSTICS COM 74834L100 3,764,061 730,146 383,196
2019-05-13 2019-03-31 13F/A-1 QUEST DIAGNOSTICS COM 74834L100 3,033,915 2,989,242 6,691.38 272,811 7,233.63 0.3614
2019-05-03 2019-03-31 13F QUEST DIAGNOSTICS COM 74834L100 3,033,915 2,989,242 272,811
2019-02-07 2018-12-31 13F QUEST DIAGNOSTICS COM 74834L100 44,673 -17,335 -27.96 3,720 -44.40 0.0053
2018-11-14 2018-09-30 13F QUEST DIAGNOSTICS COM 74834L100 62,008 2,401 4.03 6,691 2.11 0.0078
2018-08-03 2018-06-30 13F QUEST DIAGNOSTICS COM 74834L100 59,607 3,998 7.19 6,553 17.48 0.0079
2018-05-04 2018-03-31 13F QUEST DIAGNOSTICS COM 74834L100 55,609 55,609 5,578 0.0067
2017-11-02 2017-09-30 13F QUEST DIAGNOSTICS COM 74834L100 0 -853,537 -100.00 0 -100.00
2017-08-02 2017-06-30 13F QUEST DIAGNOSTICS COM 74834L100 853,537 -141,025 -14.18 94,879 -2.84 0.1207
2017-05-03 2017-03-31 13F QUEST DIAGNOSTICS COM 74834L100 994,562 125,954 14.50 97,656 22.34 0.1247
2017-02-06 2016-12-31 13F QUEST DIAGNOSTICS COM 74834L100 868,608 868,608 79,825 0.1050
2016-05-12 2016-03-31 13F QUEST DIAGNOSTICS COM 74834L100 0 -2,630,191 -100.00 0 -100.00
2016-02-08 2015-12-31 13F QUEST DIAGNOSTICS COM 74834L100 2,630,191 -1,227,114 -31.81 187,112 -21.09 0.2680
2015-11-10 2015-09-30 13F QUEST DIAGNOSTICS COM 74834L100 3,857,305 984,379 34.26 237,109 13.81 0.3614
2015-08-10 2015-06-30 13F QUEST DIAGNOSTICS COM 74834L100 2,872,926 -206,030 -6.69 208,345 -11.95 0.2993
2015-05-05 2015-03-31 13F QUEST DIAGNOSTICS COM 74834L100 3,078,956 -94,735 -2.99 236,617 11.18 0.3523
2015-02-09 2014-12-31 13F QUEST DIAGNOSTICS COM 74834L100 3,173,691 -285,968 -8.27 212,828 1.38 0.3194
2014-11-12 2014-09-30 13F QUEST DIAGNOSTICS COM 74834L100 3,459,659 228,367 7.07 209,933 10.70 0.3407
2014-08-08 2014-06-30 13F QUEST DIAGNOSTICS COM 74834L100 3,231,292 -623,716 -16.18 189,645 -15.06 0.3176
2014-05-07 2014-03-31 13F QUEST DIAGNOSTICS COM 74834L100 3,855,008 1,672,121 76.60 223,282 91.05 0.4073
2014-02-06 2013-12-31 13F QUEST DIAGNOSTICS COM 74834L100 2,182,887 248,255 12.83 116,872 -2.23 0.2396
2013-11-12 2013-09-30 13F QUEST DIAGNOSTICS COM 74834L100 1,934,632 1,926,277 23,055.38 119,541 23,478.11 0.2883
2013-08-01 2013-06-30 13F QUEST DIAGNOSTICS COM 74834L100 8,355 8,355 507 0.0014
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.