CoStar Group, Inc.
US ˙ NasdaqGS ˙ US22160N1090

SecurityCSGP / CoStar Group, Inc.
InstitutionBaillie Gifford & Co
Latest Disclosed Ownership13,610,922 shares
Latest Disclosed Value $ 549,064,593
Baillie Gifford & Co reports 5.24% increase in ownership of CSGP / CoStar Group, Inc.

On May 8, 2026 - Baillie Gifford & Co filed a 13F-HR form disclosing ownership of 13,610,922 shares of CoStar Group, Inc. (US:CSGP) valued at $549,064,593 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 23, 2026 disclosing 12,933,185 shares of CoStar Group, Inc.. This represents a change in shares of 5.24% during the quarter. The current value of the position is $461,274,147 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)
2026-05-08 2026-03-31 13F CoStar Group COM 22160N109 13,610,922 677,737 5.24 549,065 -36.86 0.5609
2026-01-23 2025-12-31 13F CoStar Group COM 22160N109 12,933,185 4,691,543 56.92 869,627 25.06 0.7226
2025-10-31 2025-09-30 13F CoStar Group COM 22160N109 8,241,642 -298,727 -3.50 695,347 1.27 0.5151
2025-08-06 2025-06-30 13F CoStar Group COM 22160N109 8,540,369 104,170 1.23 686,646 2.73 0.5128
2025-05-07 2025-03-31 13F CoStar Group COM 22160N109 8,436,199 524,601 6.63 668,400 18.01 0.5833
2025-01-31 2024-12-31 13F CoStar Group COM 22160N109 7,911,598 -887,533 -10.09 566,391 -14.68 0.4352
2024-11-05 2024-09-30 13F CoStar Group COM 22160N109 8,799,131 -252,650 -2.79 663,806 -1.09 0.4967
2024-07-25 2024-06-30 13F CoStar Group COM 22160N109 9,051,781 -201,972 -2.18 671,099 -24.93 0.5228
2024-05-01 2024-03-31 13F CoStar Group COM 22160N109 9,253,753 -270,343 -2.84 893,913 7.40 0.6953
2024-01-26 2023-12-31 13F CoStar Group COM 22160N109 9,524,096 -2,114,502 -18.17 832,311 -6.99 0.6596
2023-11-13 2023-09-30 13F CoStar Group COM 22160N109 11,638,598 -295,446 -2.48 894,892 -15.75 0.8165
2023-07-28 2023-06-30 13F CoStar Group COM 22160N109 11,934,044 -406,931 -3.30 1,062,130 25.00 0.9029
2023-05-03 2023-03-31 13F CoStar Group COM 22160N109 12,340,975 -333,556 -2.63 849,676 -13.25 0.7666
2023-03-10 2022-12-31 13F/A-1 CoStar Group COM 22160N109 12,674,531 -259,830 -2.01 979,488 8.73 1.0207
2023-01-24 2022-12-31 13F CoStar Group COM 22160N109 12,674,531 -259,830 979 0.3794
2022-10-27 2022-09-30 13F CoStar Group COM 22160N109 12,934,361 -223,511 -1.70 900,878 13.34 0.9288
2022-08-08 2022-06-30 13F CoStar Group COM 22160N109 13,157,872 -255,075 -1.90 794,866 -11.03 0.8152
2022-05-05 2022-03-31 13F CoStar Group COM 22160N109 13,412,947 -779,650 -5.49 893,437 -20.35 0.6263
2022-01-20 2021-12-31 13F CoStar Group COM 22160N109 14,192,597 1,655,617 13.21 1,121,641 3.96 0.6155
2021-10-19 2021-09-30 13F CoStar Group COM 22160N109 12,536,980 536,810 4.47 1,078,933 8.56 0.5645
2021-08-02 2021-06-30 13F CoStar Group COM 22160N109 12,000,170 10,852,735 945.83 993,853 5.39 0.4843
2021-05-06 2021-03-31 13F CoStar Group COM 22160N109 1,147,435 669,740 140.20 943,066 113.59 0.5276
2021-02-10 2020-12-31 13F CoStar Group COM 22160N109 477,695 24,168 5.33 441,525 14.73 0.2460
2020-11-12 2020-09-30 13F CoStar Group COM 22160N109 453,527 11,772 2.66 384,823 22.58 0.2650
2020-08-12 2020-06-30 13F CoStar Group COM 22160N109 441,755 35,421 8.72 313,942 31.57 0.2392
2020-05-08 2020-03-31 13F CoStar Group COM 22160N109 406,334 -4,198 -1.02 238,604 -2.86 0.2585
2020-02-10 2019-12-31 13F CoStar Group COM 22160N109 410,532 16,818 4.27 245,622 5.17 0.2374
2019-11-07 2019-09-30 13F CoStar Group COM 22160N109 393,714 -1,614 -0.41 233,551 6.63 0.2656
2019-08-08 2019-06-30 13F CoStar Group COM 22160N109 395,328 70,439 21.68 219,035 44.54 0.2324
2019-05-01 2019-03-31 13F CoStar Group COM 22160N109 324,889 5,010 1.57 151,535 40.43 0.1658
2019-02-14 2018-12-31 13F CoStar Group COM 22160N109 319,879 90,619 39.53 107,909 11.84 0.1402
2018-11-13 2018-09-30 13F CoStar Group COM 22160N109 229,260 14,340 6.67 96,482 8.79 0.1042
2018-07-17 2018-06-30 13F CoStar Group COM 22160N109 214,920 15,279 7.65 88,683 22.48 0.0957
2018-05-10 2018-03-31 13F CoStar Group COM 22160N109 199,641 23,354 13.25 72,405 38.31 0.0849
2018-02-13 2017-12-31 13F CoStar Group COM 22160N109 176,287 1,553 0.89 52,349 11.68 0.0651
2017-10-20 2017-09-30 13F CoStar Group COM 22160N109 174,734 1,564 0.90 46,873 2.68 0.0593
2017-08-10 2017-06-30 13F CoStar Group COM 22160N109 173,170 -2,880 -1.64 45,648 25.13 0.0614
2017-05-12 2017-03-31 13F CoStar Group COM 22160N109 176,050 -3,666 -2.04 36,481 7.70 0.0531
2017-02-14 2016-12-31 13F CoStar Group COM 22160N109 179,716 116 0.06 33,874 -12.90 0.0557
2016-11-09 2016-09-30 13F CoStar Group COM 22160N109 179,600 179,600 38,889 0.0608
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.