CoStar Group, Inc.
MX ˙ BMV ˙ US22160N1090
DIESES SYMBOL IST NICHT MEHR AKTIV
SecurityMX:CSGP / CoStar Group, Inc.
InstitutionBlair William & Co/il
Latest Disclosed Ownership900,313 shares
Latest Disclosed Value $ 36,318,631
Blair William & Co/il reports 55.51% decrease in ownership of CSGP / CoStar Group, Inc.

On May 8, 2026 - Blair William & Co/il filed a 13F-HR form disclosing ownership of 900,313 shares of CoStar Group, Inc. (MX:CSGP) valued at $36,318,631 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 2,023,523 shares of CoStar Group, Inc.. This represents a change in shares of -55.51% during the quarter.

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.

Upgrade to unlock premium data and export to Excel .

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)
2026-05-08 2026-03-31 13F COSTAR GROUP COM 22160N109 900,313 -1,123,210 -55.51 36,319 -73.31 0.1041
2026-02-17 2025-12-31 13F COSTAR GROUP COM 22160N109 2,023,523 -1,104,950 -35.32 136,062 -48.45 0.3652
2025-11-12 2025-09-30 13F COSTAR GROUP COM 22160N109 3,128,473 257,311 8.96 263,949 14.34 0.7026
2025-07-24 2025-06-30 13F COSTAR GROUP COM 22160N109 2,871,162 -32,356 -1.11 230,841 0.35 0.6412
2025-05-09 2025-03-31 13F COSTAR GROUP COM 22160N109 2,903,518 -490,433 -14.45 230,046 -5.32 0.6938
2025-02-12 2024-12-31 13F COSTAR GROUP COM 22160N109 3,393,951 -456,885 -11.86 242,973 -16.36 0.7068
2024-11-12 2024-09-30 13F COSTAR GROUP COM 22160N109 3,850,836 -546,902 -12.44 290,507 -10.90 0.8532
2024-08-12 2024-06-30 13F COSTAR GROUP COM 22160N109 4,397,738 -22,040 -0.50 326,048 -23.63 1.0057
2024-05-09 2024-03-31 13F COSTAR GROUP COM 22160N109 4,419,778 26,800 0.61 426,951 11.21 1.3410
2024-02-12 2023-12-31 13F COSTAR GROUP COM 22160N109 4,392,978 201,969 4.82 383,902 19.13 1.3082
2023-11-09 2023-09-30 13F COSTAR GROUP COM 22160N109 4,191,009 251,182 6.38 322,247 -8.10 1.2358
2023-08-11 2023-06-30 13F COSTAR GROUP COM 22160N109 3,939,827 184,794 4.92 350,645 35.63 1.2845
2023-05-12 2023-03-31 13F COSTAR GROUP COM 22160N109 3,755,033 44,732 1.21 258,534 -9.83 1.0327
2023-02-10 2022-12-31 13F COSTAR GROUP COM 22160N109 3,710,301 256,608 7.43 286,732 19.20 1.2468
2022-11-09 2022-09-30 13F COSTAR GROUP COM 22160N109 3,453,693 244,909 7.63 240,550 24.10 1.1048
2022-08-10 2022-06-30 13F COSTAR GROUP COM 22160N109 3,208,784 453,649 16.47 193,843 5.63 0.8600
2022-05-13 2022-03-31 13F COSTAR GROUP COM 22160N109 2,755,135 -40,211 -1.44 183,520 -16.93 0.6433
2022-02-14 2021-12-31 13F COSTAR GROUP COM 22160N109 2,795,346 71,440 2.62 220,916 -5.76 0.6929
2021-11-12 2021-09-30 13F COSTAR GROUP COM 22160N109 2,723,906 48,540 1.81 234,419 5.80 0.7980
2021-08-12 2021-06-30 13F COSTAR GROUP COM 22160N109 2,675,366 2,412,720 918.62 221,574 2.64 0.7678
2021-05-13 2021-03-31 13F COSTAR GROUP COM 22160N109 262,646 4,054 1.57 215,866 -9.68 0.8143
2021-02-09 2020-12-31 13F COSTAR GROUP COM 22160N109 258,592 1,224 0.48 239,011 9.45 0.8762
2020-11-06 2020-09-30 13F COSTAR GROUP COM 22160N109 257,368 1,839 0.72 218,379 20.25 0.9263
2020-08-12 2020-06-30 13F COSTAR GROUP COM 22160N109 255,529 4,572 1.82 181,597 23.23 0.8659
2020-05-11 2020-03-31 13F COSTAR GROUP COM 22160N109 250,957 -4,872 -1.90 147,364 -3.72 0.9211
2020-02-13 2019-12-31 13F COSTAR GROUP COM 22160N109 255,829 3,759 1.49 153,062 2.36 0.7867
2019-11-12 2019-09-30 13F COSTAR GROUP COM 22160N109 252,070 -5,051 -1.96 149,528 4.96 0.8616
2019-08-13 2019-06-30 13F COSTAR GROUP COM 22160N109 257,121 -1,932 -0.75 142,460 17.90 0.8146
2019-05-14 2019-03-31 13F COSTAR GROUP COM 22160N109 259,053 9,971 4.00 120,827 43.80 0.7366
2019-02-14 2018-12-31 13F COSTAR GROUP COM 22160N109 249,082 -4,215 -1.66 84,025 -21.18 0.6136
2018-11-13 2018-09-30 13F COSTAR GROUP COM 22160N109 253,297 -2,931 -1.14 106,598 0.82 0.6531
2018-08-13 2018-06-30 13F COSTAR GROUP COM 22160N109 256,228 -16,278 -5.97 105,727 6.98 0.7191
2018-05-15 2018-03-31 13F COSTAR GROUP COM 22160N109 272,506 -70,270 -20.50 98,832 -2.90 0.6989
2018-02-14 2017-12-31 13F COSTAR GROUP COM 22160N109 342,776 -8,348 -2.38 101,787 8.07 0.6909
2017-11-13 2017-09-30 13F COSTAR GROUP COM 22160N109 351,124 -4,450 -1.25 94,189 0.49 0.7063
2017-08-04 2017-06-30 13F COSTAR GROUP COM 22160N109 355,574 -10,757 -2.94 93,729 24.62 0.7038
2017-05-10 2017-03-31 13F COSTAR GROUP COM 22160N109 366,331 14,492 4.12 75,214 13.41 0.6062
2017-02-14 2016-12-31 13F COSTAR GROUP COM 22160N109 351,839 -321 -0.09 66,318 -13.03 0.5932
2016-11-14 2016-09-30 13F COSTAR GROUP COM 22160N109 352,160 23,063 7.01 76,253 5.97 0.6740
2016-08-08 2016-06-30 13F COSTAR GROUP COM 22160N109 329,097 -10,280 -3.03 71,960 12.68 0.6710
2016-05-16 2016-03-31 13F COSTAR GROUP COM 22160N109 339,377 8,365 2.53 63,861 -6.66 0.6012
2016-02-16 2015-12-31 13F COSTAR GROUP COM 22160N109 331,012 -52,166 -13.61 68,417 3.17 0.6424
2015-11-12 2015-09-30 13F COSTAR GROUP COM 22160N109 383,178 -1,025,777 -72.80 66,312 -76.61 0.5737
2015-08-03 2015-06-30 13F COSTAR GROUP COM 22160N109 1,408,955 6,297 0.45 283,566 2.19 0.4241
2015-05-11 2015-03-31 13F COSTAR GROUP COM 22160N109 1,402,658 1,402,658 0.00 277,488 0.4272
2015-02-05 2014-12-31 13F COSTAR GROUP COM 22160N109 0 -1,270,270 -100.00 0 -100.00
2014-11-04 2014-09-30 13F COSTAR GROUP COM 22160N109 1,270,270 -10,204 -0.80 197,578 -2.45 0.3380
2014-08-01 2014-06-30 13F COSTAR GROUP COM 22160N109 1,280,474 319,872 33.30 202,532 12.91 0.3307
2014-05-06 2014-03-31 13F COSTAR GROUP COM 22160N109 960,602 7,945 0.83 179,382 2.01 0.2967
2014-02-11 2013-12-31 13F COSTAR GROUP COM 22160N109 952,657 -109,766 -10.33 175,841 -1.43 0.2906
2013-11-12 2013-09-30 13F COSTAR GROUP COM 22160N109 1,062,423 -6,034 -0.56 178,393 29.36 0.3172
2013-08-07 2013-06-30 13F COSTAR GROUP COM 22160N109 1,068,457 1,068,457 137,905 0.2727
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.