CoStar Group, Inc.
US ˙ NasdaqGS ˙ US22160N1090

SecurityCSGP / CoStar Group, Inc.
InstitutionVestmark Advisory Solutions, Inc.
Latest Disclosed Ownership13,940 shares
Latest Disclosed Value $ 562,340
Vestmark Advisory Solutions, Inc. reports 45.37% increase in ownership of CSGP / CoStar Group, Inc.

On May 15, 2026 - Vestmark Advisory Solutions, Inc. filed a 13F-HR form disclosing ownership of 13,940 shares of CoStar Group, Inc. (US:CSGP) valued at $562,340 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 6, 2026 disclosing 9,589 shares of CoStar Group, Inc.. This represents a change in shares of 45.37% during the quarter. The current value of the position is $465,596 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)
2026-05-15 2026-03-31 13F COSTAR GROUP COM 22160N109 13,940 4,351 45.37 562 -12.73 0.0039
2026-02-06 2025-12-31 13F COSTAR GROUP COM 22160N109 9,589 -3,655 -27.60 645 -42.35 0.0087
2025-11-10 2025-09-30 13F COSTAR GROUP COM 22160N109 13,244 -91 -0.68 1,117 4.20 0.0213
2025-08-06 2025-06-30 13F COSTAR GROUP COM 22160N109 13,335 2,295 20.79 1,072 22.65 0.0155
2025-05-13 2025-03-31 13F COSTAR GROUP COM 22160N109 11,040 3,973 56.22 875 73.07 0.0225
2025-02-06 2024-12-31 13F COSTAR GROUP COM 22160N109 7,067 7,067 506 0.0174
2024-08-12 2024-06-30 13F COSTAR GROUP COM 22160N109 0 -3,567 -100.00 0 -100.00
2024-05-15 2024-03-31 13F COSTAR GROUP COM 22160N109 3,567 -317 -8.16 345 1.47 0.0148
2024-02-06 2023-12-31 13F COSTAR GROUP COM 22160N109 3,884 -4,116 -51.45 339 -44.88 0.0172
2023-11-06 2023-09-30 13F COSTAR GROUP COM 22160N109 8,000 -19,040 -70.41 615 -74.44 0.0447
2023-08-07 2023-06-30 13F COSTAR GROUP COM 22160N109 27,040 -1,835 -6.35 2,407 21.03 0.0916
2023-05-09 2023-03-31 13F COSTAR GROUP COM 22160N109 28,875 965 3.46 1,988 -7.79 0.0861
2023-01-20 2022-12-31 13F COSTAR GROUP COM 22160N109 27,910 -1,130 -3.89 2,157 6.57 0.1051
2022-11-03 2022-09-30 13F COSTAR GROUP COM 22160N109 29,040 -487 -1.65 2,023 13.46 0.1128
2022-08-04 2022-06-30 13F COSTAR GROUP COM 22160N109 29,527 -827 -2.72 1,783 -11.78 0.1018
2022-04-27 2022-03-31 13F COSTAR GROUP COM 22160N109 30,354 -1,286 -4.06 2,021 -19.16 0.1144
2022-01-31 2021-12-31 13F COSTAR GROUP COM 22160N109 31,640 951 3.10 2,500 -5.34 0.1411
2021-11-15 2021-09-30 13F COSTAR GROUP COM 22160N109 30,689 2,060 7.20 2,641 11.39 0.1789
2021-08-09 2021-06-30 13F COSTAR GROUP COM 22160N109 28,629 25,657 863.29 2,371 -2.95 0.1687
2021-05-10 2021-03-31 13F COSTAR GROUP COM 22160N109 2,972 1,089 57.83 2,443 40.40 0.2167
2021-02-04 2020-12-31 13F COSTAR GROUP COM 22160N109 1,883 146 8.41 1,740 18.05 0.1952
2020-10-19 2020-09-30 13F COSTAR GROUP COM 22160N109 1,737 416 31.49 1,474 56.98 0.1980
2020-08-13 2020-06-30 13F COSTAR GROUP COM 22160N109 1,321 111 9.17 939 32.07 0.1453
2020-05-06 2020-03-31 13F COSTAR GROUP COM 22160N109 1,210 1,210 711 0.1390
2020-02-14 2019-12-31 13F COSTAR GROUP COM 22160N109 0 -1,261 -100.00 0 -100.00
2019-11-05 2019-09-30 13F COSTAR GROUP COM 22160N109 1,261 -70 -5.26 748 1.49 0.1213
2019-08-20 2019-06-30 13F COSTAR GROUP COM 22160N109 1,331 65 5.13 737 24.92 0.1261
2019-05-14 2019-03-31 13F COSTAR GROUP COM 22160N109 1,266 1,266 590 0.1052
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.