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Costar Group, Inc.

CSGP
Exchange
Nasdaq
Industry
Services-Business Services, NEC
SEC CIK
0001057352

No open-market purchases or sales by Costar Group, Inc. insiders were filed in the last 90 days; 764 institutions reported holding it in 13F filings for Q2 2026, worth $11.7B in total; superinvestors Akre Capital Management and Weitz Investment Management hold it.

Four kinds of short-selling data, each measuring something different:

  • Short interest: shares sold short and not yet bought back, as of a settlement date. FINRA publishes it twice a month, about eight business days after the settlement date.
  • Daily short volume: shares sold short each day in off-exchange trades reported to FINRA. It counts trades, not open positions, and is published the next day.
  • Fails-to-deliver: shares not delivered by the settlement date. The SEC publishes them twice a month, about two weeks late.
  • ATS (dark pool) volume: weekly volume on alternative trading systems and other off-exchange venues. FINRA publishes it two to four weeks after the week.

More in the glossary.

Short interest

Shares sold short and not yet bought back, from FINRA, on every settlement date in the last two years.

Short interest
12.5M
Shares, settlement Oct 30, 2026
Change
−2.49M
−16.6% vs. Oct 15, 2026
Days to cover
1.73
Short interest ÷ average daily volume
Average daily volume
7.24M
Shares, as reported by FINRA
Short interest by settlement date
Oct 31, 2024: 11,919,931 sharesNov 15, 2024: 11,056,364 sharesNov 29, 2024: 11,122,290 sharesDec 13, 2024: 11,750,605 sharesDec 31, 2024: 12,704,164 sharesJan 15, 2025: 13,369,768 sharesJan 31, 2025: 12,991,755 sharesFeb 14, 2025: 14,904,634 sharesFeb 28, 2025: 15,772,945 sharesMar 14, 2025: 16,195,891 sharesMar 31, 2025: 17,487,403 sharesApr 15, 2025: 17,711,428 sharesApr 30, 2025: 17,624,905 sharesMay 15, 2025: 17,234,159 sharesMay 30, 2025: 15,965,072 sharesJun 13, 2025: 16,809,810 sharesJun 30, 2025: 16,229,429 sharesJul 15, 2025: 17,026,626 sharesJul 31, 2025: 15,861,840 sharesAug 15, 2025: 16,527,066 sharesAug 29, 2025: 16,659,521 sharesSep 15, 2025: 17,118,330 sharesSep 30, 2025: 15,408,940 sharesOct 15, 2025: 15,724,532 sharesOct 31, 2025: 16,725,267 sharesNov 14, 2025: 18,092,722 sharesNov 28, 2025: 17,534,153 sharesDec 15, 2025: 17,547,557 sharesDec 31, 2025: 16,266,374 sharesJan 15, 2026: 14,419,195 sharesJan 30, 2026: 16,612,914 sharesFeb 13, 2026: 19,341,189 sharesFeb 27, 2026: 26,150,995 sharesMar 13, 2026: 23,958,704 sharesMar 31, 2026: 21,977,041 sharesApr 15, 2026: 16,639,852 sharesApr 30, 2026: 17,590,854 sharesMay 15, 2026: 18,639,692 sharesMay 29, 2026: 15,095,773 sharesJun 15, 2026: 17,109,207 sharesJun 30, 2026: 15,266,339 sharesJul 15, 2026: 16,321,416 sharesJul 31, 2026: 16,312,412 sharesAug 14, 2026: 16,691,379 sharesAug 31, 2026: 18,901,758 sharesSep 15, 2026: 14,839,529 sharesSep 30, 2026: 13,284,736 sharesOct 15, 2026: 14,988,751 sharesOct 30, 2026: 12,499,298 shares
Short interest in CSGP by settlement date
Settlement dateShort interestChangeChange %Avg. daily volumeDays to cover
Oct 30, 202612.5M−2.49M−16.6%7.24M1.73
Oct 15, 202615.0M+1.70M+12.8%5.20M2.88
Sep 30, 202613.3M−1.55M−10.5%6.73M1.97
Sep 15, 202614.8M−4.06M−21.5%5.53M2.68
Aug 31, 202618.9M+2.21M+13.2%7.54M2.51
Aug 14, 202616.7M+379.0K+2.3%5.99M2.79
Jul 31, 202616.3M−9.00K−0.1%8.52M1.92
Jul 15, 202616.3M+1.06M+6.9%6.66M2.45
Jun 30, 202615.3M−1.84M−10.8%8.02M1.90
Jun 15, 202617.1M+2.01M+13.3%7.15M2.39
May 29, 202615.1M−3.54M−19.0%6.28M2.40
May 15, 202618.6M+1.05M+6.0%9.86M1.89
Apr 30, 202617.6M+951.0K+5.7%6.30M2.79
Apr 15, 202616.6M−5.34M−24.3%6.28M2.65
Mar 31, 202622.0M−1.98M−8.3%6.69M3.28
Mar 13, 202624.0M−2.19M−8.4%5.25M4.56
Feb 27, 202626.2M+6.81M+35.2%6.98M3.75
Feb 13, 202619.3M+2.73M+16.4%7.97M2.43
Jan 30, 202616.6M+2.19M+15.2%6.61M2.51
Jan 15, 202614.4M−1.85M−11.4%7.55M1.91
Dec 31, 202516.3M−1.28M−7.3%3.93M4.14
Dec 15, 202517.5M+13.4K+0.1%3.39M5.17
Nov 28, 202517.5M−558.6K−3.1%4.62M3.80
Nov 14, 202518.1M+1.37M+8.2%4.50M4.02
Oct 31, 202516.7M+1.00M+6.4%4.15M4.03
Oct 15, 202515.7M+315.6K+2.1%3.07M5.13
Sep 30, 202515.4M−1.71M−10.0%3.08M5.00
Sep 15, 202517.1M+458.8K+2.8%2.25M7.61
Aug 29, 202516.7M+132.5K+0.8%2.25M7.39
Aug 15, 202516.5M+665.2K+4.2%3.05M5.41
Jul 31, 202515.9M−1.16M−6.8%3.36M4.73
Jul 15, 202517.0M+797.2K+4.9%2.30M7.39
Jun 30, 202516.2M−580.4K−3.5%3.04M5.33
Jun 13, 202516.8M+844.7K+5.3%2.75M6.11
May 30, 202516.0M−1.27M−7.4%2.94M5.43
May 15, 202517.2M−390.7K−2.2%2.95M5.84
Apr 30, 202517.6M−86.5K−0.5%4.06M4.34
Apr 15, 202517.7M+224.0K+1.3%3.82M4.64
Mar 31, 202517.5M+1.29M+8.0%2.71M6.46
Mar 14, 202516.2M+422.9K+2.7%4.53M3.58
Feb 28, 202515.8M+868.3K+5.8%4.80M3.29
Feb 14, 202514.9M+1.91M+14.7%2.54M5.86
Jan 31, 202513.0M−378.0K−2.8%2.15M6.03
Jan 15, 202513.4M+665.6K+5.2%2.60M5.15
Dec 31, 202412.7M+953.6K+8.1%2.82M4.51
Dec 13, 202411.8M+628.3K+5.7%2.05M5.72
Nov 29, 202411.1M+65.9K+0.6%2.58M4.31
Nov 15, 202411.1M−863.6K−7.2%2.60M4.25
Oct 31, 202411.9M+3.85M+47.6%4.47M2.66

Fails-to-deliver

Shares that weren't delivered by the settlement date, from the SEC, for the last 30 dates with fails. The price is the previous day's closing price published by the SEC.

Fails-to-deliver in CSGP by settlement date
Settlement dateSharesPriceValue
Sep 30, 202616,723$26.95$450.7K
Sep 9, 20263,694$30.34$112.1K
Sep 3, 202619,552$31.26$611.2K
Sep 1, 202679,443$32.07$2.55M
Aug 31, 202662,865$32.22$2.03M
Aug 26, 20265,560$32.81$182.4K
Aug 19, 20261$31.38$31.38
Aug 11, 20264,200$31.48$132.2K
Aug 3, 202681$28.76$2.33K
Jul 28, 2026400$29.17$11.7K
Jun 22, 202635,999$30.12$1.08M
Jun 18, 202626,104$30.46$795.1K
Jun 16, 2026323$32.04$10.3K
May 26, 20265,309$33.95$180.2K
May 22, 202611,970$33.93$406.1K
May 18, 202637,704$32.68$1.23M
May 14, 20261,288$31.97$41.2K
May 13, 202649,798$33.05$1.65M
May 8, 202653,143$34.98$1.86M
Apr 21, 202610$40.06$400.6
Apr 20, 2026651$39.72$25.9K
Apr 16, 2026171$39.31$6.72K
Apr 15, 20266$37.60$225.6
Apr 14, 2026243$37.06$9.01K
Apr 10, 20262,690$37.32$100.4K
Apr 1, 20262,800$40.34$113.0K
Mar 31, 20261,919$40.88$78.4K
Mar 25, 202643$41.46$1.78K
Mar 24, 2026491,248$42.91$21.1M
Mar 23, 2026491,261$42.90$21.1M

Daily short volume

Off-exchange short-sale volume, not short interest: shares sold short each day in trades reported to FINRA, for the last 30 trading days.

The short volume ratio isn't a sentiment gauge: market makers sell short to fill buy orders and to hedge, so short sales are usually about half of off-exchange volume.

Off-exchange short volume in CSGP by trade date
Trade dateShort volumeShort exemptOff-exchange volumeShort volume ratio
Nov 10, 2026233,6491,1691,036,91322.5%
Nov 9, 2026863,3201,2792,110,57940.9%
Nov 6, 2026871,3621762,341,29637.2%
Nov 5, 2026470,5837,3372,209,88521.3%
Nov 4, 2026460,4691,8962,085,77222.1%
Nov 3, 2026902,9124431,612,26656.0%
Nov 2, 2026906,36724,5042,164,87541.9%
Oct 30, 20261,299,3077,7453,286,06039.5%
Oct 29, 2026541,16947,9762,832,72919.1%
Oct 28, 20262,231,877251,6737,752,66828.8%
Oct 27, 2026809,94302,674,52930.3%
Oct 26, 2026522,8401,3102,037,13925.7%
Oct 23, 2026884,6267322,875,63330.8%
Oct 22, 2026569,2672843,211,55817.7%
Oct 21, 2026372,0808921,199,88931.0%
Oct 20, 2026535,249391,691,80931.6%
Oct 19, 2026410,47001,185,45934.6%
Oct 16, 2026579,52402,106,61127.5%
Oct 15, 2026771,0995,4122,163,63035.6%
Oct 14, 2026677,5827511,601,78342.3%
Oct 13, 20261,076,5884,3012,213,79648.6%
Oct 12, 2026472,986651,095,97143.2%
Oct 9, 2026878,4732151,540,58657.0%
Oct 8, 20261,060,1251,4872,603,15740.7%
Oct 7, 2026487,819861,213,47240.2%
Oct 6, 2026507,12851,449,35635.0%
Oct 5, 2026691,8844,3881,890,38336.6%
Oct 2, 2026658,119311,271,80751.7%
Oct 1, 2026688,020111,695,06640.6%
Sep 30, 2026773,5821,6272,203,87235.1%

ATS (dark pool) volume

Weekly volume on alternative trading systems (ATS) and other off-exchange (OTC) venues, from FINRA, for the last 12 weeks. ATS share is ATS volume ÷ (ATS + OTC volume), not a share of all trading.

Weekly ATS and OTC volume in CSGP
Week ofTierATS sharesATS tradesOther OTC sharesOther OTC tradesATS share
Oct 19, 2026T16,914,424105,7116,051,04123,09553.3%
Oct 12, 2026T16,212,04388,0755,369,33524,09453.6%
Oct 5, 2026T15,706,50085,6134,781,59723,78654.4%
Sep 28, 2026T15,835,70096,9784,728,73924,32555.2%
Sep 21, 2026T15,857,011101,5546,566,09823,99547.1%
Sep 14, 2026T15,887,011106,2807,128,92126,25745.2%
Sep 7, 2026T15,875,61897,2744,241,19620,08958.1%
Aug 31, 2026T17,325,519115,17511,117,21727,35739.7%
Aug 24, 2026T17,080,171117,2573,147,09823,75669.2%
Aug 17, 2026T17,887,984109,8773,766,99427,90967.7%
Aug 10, 2026T18,096,756126,3963,276,37926,82971.2%
Aug 3, 2026T17,785,334143,9805,652,29031,82157.9%