CoStar Group, Inc.
MX ˙ BMV ˙ US22160N1090
DETTE SYMBOL ER IKKE LÆNGERE AKTIVT
SecurityMX:CSGP / CoStar Group, Inc.
InstitutionMassmutual Trust Co Fsb/adv
Latest Disclosed Ownership2,077 shares
Latest Disclosed Value $ 83,786
Massmutual Trust Co Fsb/adv reports 16.75% increase in ownership of CSGP / CoStar Group, Inc.

On April 13, 2026 - Massmutual Trust Co Fsb/adv filed a 13F-HR form disclosing ownership of 2,077 shares of CoStar Group, Inc. (MX:CSGP) valued at $83,786 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 7, 2026 disclosing 1,779 shares of CoStar Group, Inc.. This represents a change in shares of 16.75% 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.

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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)
2026-04-13 2026-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 2,077 298 16.75 84 -30.25 0.0023
2026-01-07 2025-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 1,779 -289 -13.97 120 -31.61 0.0031
2025-10-22 2025-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 2,068 110 5.62 174 10.83 0.0044
2025-07-09 2025-06-30 13F CoStar Group Common / Ordinary Stock 22160N109 1,958 -64 -3.17 157 -1.87 0.0042
2025-04-01 2025-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 2,022 -28 -1.37 160 9.59 0.0046
2025-01-16 2024-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 2,050 -296 -12.62 147 -17.05 0.0041
2024-10-02 2024-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 2,346 -115 -4.67 177 -3.30 0.0050
2024-07-02 2024-06-30 13F CoStar Group Common / Ordinary Stock 22160N109 2,461 -723 -22.71 182 -40.72 0.0055
2024-04-09 2024-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 3,184 -1,588 -33.28 308 -26.38 0.0096
2024-01-03 2023-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 4,772 -278 -5.50 417 7.47 0.0140
2023-10-04 2023-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 5,050 39 0.78 388 -12.81 0.0143
2023-08-02 2023-06-30 13F CoStar Group Common / Ordinary Stock 22160N109 5,011 180 3.73 446 34.04 0.0160
2023-04-11 2023-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 4,831 169 3.63 333 0.0127
2023-01-06 2022-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 4,662 -34 -0.72 0 0.0148
2022-10-07 2022-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 4,696 -829 -15.00 0 0.0148
2022-07-07 2022-06-30 13F CoStar Group Common / Ordinary Stock 22160N109 5,525 -56 -1.00 0 0.0145
2022-04-08 2022-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 5,581 636 12.86 0 0.0141
2022-02-09 2021-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 4,945 206 4.35 0 0.0145
2021-11-12 2021-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 4,739 4,739 0 0.0169
2021-05-17 2021-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 0 -5 -100.00 0 0.0000
2021-02-16 2020-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 5 5 0 0.0003
2020-11-13 2020-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 0 -2 -100.00 0 -100.00
2020-08-13 2020-06-30 13F CoStar Group Common / Ordinary Stock 22160N109 2 2 1 0.0001
2020-05-15 2020-03-31 13F CoStar Group Common / Ordinary Stock 22160N109 0 -26 -100.00 0 -100.00
2020-05-15 2019-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 26 19 271.43 16 300.00 0.0010
2019-11-14 2019-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 7 7 4 0.0003
2019-02-26 2018-12-31 13F CoStar Group Common / Ordinary Stock 22160N109 0 -23 -100.00 0 -100.00
2018-11-09 2018-09-30 13F CoStar Group Common / Ordinary Stock 22160N109 23 0 0.00 10 0.00 0.0007
2018-08-20 2018-06-30 13F CoStar Group Common / Ordinary Stock 22160N109 23 23 9 0.0008
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.