Caribou Biosciences (CRBU)

Caribou Biosciences on one page: short interest, daily short volume, fails to deliver, planned sales, large holders, 13F holders, earnings dates and insider trades. Listed on Nasdaq, classified by the SEC as biological products, (no diagnostic substances).

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12.6M

Short interest

settlement 2026-10-15

1.5

Days to cover

-11.5 days vs prior

52.6%

Short share of volume

2026-11-02

74,206

Fails to deliver

settlement 2026-10-08

Wed 11 Nov

Next earnings

estimated date

Insider flow, 90 days

0 buys, 0 sells

As of 2026-11-02.

Short interest

FINRA, twice a month. The newest 48 settlements in the table, 48 in the chart. JSON

As of 15 October 2026, short interest in CRBU is 12,554,864 shares, down 423,741 shares over the last month. Over the last 48 readings it ranged from 3,546,605 shares (31 October 2025) to 12,978,605 shares (15 September 2026). The latest reading sits at the top of that range. At the reported average volume of 8.1M shares a day that is 1.5 days to cover.

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Settlement	Shares short	Change	Avg daily volume	Days to cover
2026-10-15	12,554,864	-2.8%	8,136,687	1.54
2026-09-30	12,914,422	-0.5%	986,415	13.09
2026-09-15	12,978,605	+3.8%	1,367,465	9.49
2026-08-31	12,501,320	+0.3%	966,397	12.94
2026-08-14	12,465,346	+7.1%	1,042,740	11.95
2026-07-31	11,639,454	+0.4%	1,235,028	9.42
2026-07-15	11,594,287	+20.4%	2,358,728	4.92
2026-06-30	9,625,837	+27.8%	3,158,400	3.05
2026-06-15	7,531,658	+1.1%	1,815,909	4.15
2026-05-29	7,450,323	+4.4%	1,840,607	4.05
2026-05-15	7,136,627	+0.2%	1,577,443	4.52
2026-04-30	7,123,813	+5.3%	1,637,158	4.35
2026-04-15	6,768,285	+4.6%	1,233,929	5.49
2026-03-31	6,472,632	-8.3%	1,079,529	6.00
2026-03-13	7,057,089	-2.4%	1,142,965	6.17
2026-02-27	7,232,010	-6.9%	1,470,964	4.92
2026-02-13	7,768,220	+3.2%	1,352,743	5.74
2026-01-30	7,530,609	+10.8%	1,094,660	6.88
2026-01-15	6,793,288	+4.5%	999,521	6.80
2025-12-31	6,501,051	+4.2%	1,007,298	6.45
2025-12-15	6,240,758	+1.6%	962,709	6.48
2025-11-28	6,140,242	+9.3%	1,048,663	5.86
2025-11-14	5,618,833	+58.4%	8,817,899	1.00
2025-10-31	3,546,605	-3.4%	781,727	4.54
2025-10-15	3,672,865	-9.9%	1,474,267	2.49
2025-09-30	4,074,512	-0.9%	1,376,883	2.96
2025-09-15	4,112,720	+2.0%	477,773	8.61
2025-08-29	4,030,604	+3.6%	887,012	4.54
2025-08-15	3,889,653	-0.1%	1,074,456	3.62
2025-07-31	3,895,329	-15.7%	2,209,455	1.76
2025-07-15	4,622,078	-25.3%	1,513,569	3.05
2025-06-30	6,189,594	-43.5%	2,323,168	2.66
2025-06-13	10,953,629	+31.4%	1,305,799	8.39
2025-05-30	8,337,871	-12.2%	1,091,390	7.64
2025-05-15	9,494,724	+24.4%	785,089	12.09
2025-04-30	7,631,637	-19.5%	1,285,699	5.94
2025-04-15	9,480,437	-4.1%	1,069,967	8.86
2025-03-31	9,885,646	+12.0%	1,040,820	9.50
2025-03-14	8,824,727	-13.7%	938,767	9.40
2025-02-28	10,220,575	+14.7%	1,108,365	9.22
2025-02-14	8,907,755	+0.6%	1,007,204	8.84
2025-01-31	8,858,817	-18.0%	1,540,800	5.75
2025-01-15	10,802,840	+13.3%	1,726,426	6.26
2024-12-31	9,535,766	-2.7%	1,440,677	6.62
2024-12-13	9,797,621	+13.7%	1,414,756	6.93
2024-11-29	8,616,165	+16.2%	1,511,549	5.70
2024-11-15	7,417,636	-25.4%	2,178,160	3.41
2024-10-31	9,940,336	-13.6%	982,374	10.12

Daily short volume

FINRA Reg SHO, the last 30 sessions. JSON

As of 2 November 2026, the short share of CRBU volume is 52.6%, down 7.4 points over the last five sessions. Over the last 30 readings it ranged from 34.1% (27 October 2026) to 72.0% (2 October 2026). The latest reading is 5.3 points below the 30-session average of 57.9%, on 1.3M shares reported.

Date	Short volume	Total volume	Short share	Exempt
2026-11-02	695K	1.3M	52.6%	700
2026-10-30	723K	1.2M	62.3%	15,117
2026-10-29	799K	1.3M	60.6%	0
2026-10-28	271K	553K	49.0%	1,400
2026-10-27	398K	1.2M	34.1%	7,992
2026-10-26	622K	1.0M	60.1%	474
2026-10-23	658K	1.1M	61.9%	0
2026-10-22	852K	1.6M	52.1%	2,300
2026-10-21	770K	1.2M	65.0%	9,438
2026-10-20	1.0M	1.9M	53.0%	49,845
2026-10-19	1.3M	2.3M	58.2%	12,910
2026-10-16	1.2M	2.0M	59.6%	44,932
2026-10-15	1.1M	1.8M	63.4%	1,750
2026-10-14	1.5M	2.2M	71.0%	7,486
2026-10-13	1.3M	2.4M	56.2%	23,885
2026-10-12	2.2M	3.2M	67.1%	20,561
2026-10-09	3.9M	7.0M	55.9%	846,353
2026-10-08	9.6M	13.7M	70.4%	1,823,792
2026-10-07	14.0M	22.0M	63.5%	3,231,530
2026-10-06	250K	506K	49.4%	1,896
2026-10-05	371K	643K	57.7%	8
2026-10-02	296K	411K	72.0%	0
2026-10-01	154K	298K	51.6%	35
2026-09-30	154K	317K	48.6%	76
2026-09-29	144K	288K	50.0%	0
2026-09-28	213K	416K	51.1%	1,108
2026-09-25	320K	472K	67.8%	478
2026-09-24	340K	498K	68.2%	187
2026-09-23	215K	326K	65.9%	10
2026-09-22	243K	610K	39.7%	0

Fails to deliver

SEC, the last 30 settlement dates with a fail. JSON

As of 8 October 2026, the fails-to-deliver balance in CRBU is 74,206 shares, up 67,588 shares over the last settlement date. Over the last 30 readings it ranged from 1 share (21 July 2026) to 76,175 shares (14 September 2026). The latest reading sits at the top of that range.

Settlement	Shares failed	Price	Value
2026-10-08	74,206	$0.62	$46K
2026-10-06	6,618	$1.19	$8K
2026-10-05	20,102	$1.22	$25K
2026-09-29	23,133	$1.23	$28K
2026-09-28	35,767	$1.24	$44K
2026-09-22	39,148	$1.30	$51K
2026-09-21	2,139	$1.30	$3K
2026-09-14	76,175	$1.27	$97K
2026-09-11	11,830	$1.37	$16K
2026-09-10	29,230	$1.44	$42K
2026-09-09	574	$1.54	$884
2026-09-08	687	$1.57	$1K
2026-08-31	94	$1.62	$152
2026-08-21	8,755	$1.61	$14K
2026-08-19	2,330	$1.56	$4K
2026-08-14	846	$1.61	$1K
2026-08-12	187	$1.69	$316
2026-08-11	9	$1.66	$15
2026-08-06	14,842	$1.61	$24K
2026-08-04	5,978	$1.50	$9K
2026-07-31	1,092	$1.51	$2K
2026-07-21	1	$1.62	$2
2026-07-16	7,184	$1.73	$12K
2026-07-15	9	$1.75	$16
2026-07-14	9	$1.80	$16
2026-07-09	5,799	$1.94	$11K
2026-07-08	4,570	$1.92	$9K
2026-07-06	30,211	$1.82	$55K
2026-07-01	14,857	$1.76	$26K
2026-06-29	70,339	$1.68	$118K

Insider trades

SEC Form 4, newest first. JSON

No open-market insider trades were reported for CRBU in the last 90 days. The most recent filings are listed below. Latest filing: Kelly Timothy P (Chief Technology Officer) on 2026-02-25.

Date	Insider	Title	Type	Shares	Price	Value	Owned after
2026-02-25	Kelly Timothy P	Chief Technology Officer	Sell	6K	$1.93	$12K	73K
2026-02-24	Khan Ruhi Ahmad	Chief Business Officer	Sell	7K	$1.96	$14K	105K
2026-02-24	Kelly Timothy P	Chief Technology Officer	Sell	3K	$1.96	$6K	79K
2026-02-24	MCCLUNG BARBARA G	Chief Legal Officer	Sell	7K	$1.96	$14K	482K
2026-02-24	Albertson Tina M.	Chief Medical Officer	Sell	1K	$1.96	$2K	69K
2026-02-20	Ryali Sriram	Chief Financial Officer	Grant	55K	$0.00	$0	72K
2026-02-20	Haurwitz Rachel E.	President and CEO	Grant	152K	$0.00	$0	447K
2026-02-20	Khan Ruhi Ahmad	Chief Business Officer	Grant	45K	$0.00	$0	112K
2026-02-20	Kelly Timothy P	Chief Technology Officer	Grant	45K	$0.00	$0	83K
2026-02-20	MCCLUNG BARBARA G	Chief Legal Officer	Grant	45K	$0.00	$0	489K
2026-02-20	Albertson Tina M.	Chief Medical Officer	Grant	55K	$0.00	$0	70K
2025-03-14	Haurwitz Rachel E.	President and CEO	Buy	20K	$1.02	$20K	3.4M
2025-02-21	Kanner Steven	Chief Scientific Officer	Sell	4K	$1.35	$5K	432K
2025-02-21	Khan Ruhi Ahmad	Chief Business Officer	Sell	4K	$1.35	$5K	67K
2025-02-21	MCCLUNG BARBARA G	Chief Legal Officer	Sell	4K	$1.35	$5K	444K
2025-02-20	Kanner Steven	Chief Scientific Officer	Grant	38K	$0.00	$0	435K
2025-02-20	Kelly Timothy P	Chief Technology Officer	Grant	38K	$0.00	$0	38K
2025-02-20	Khan Ruhi Ahmad	Chief Business Officer	Grant	38K	$0.00	$0	71K
2025-02-20	MCCLUNG BARBARA G	Chief Legal Officer	Grant	38K	$0.00	$0	447K
2025-02-20	Albertson Tina M.	Chief Medical Officer	Grant	15K	$0.00	$0	15K
2025-02-20	Haurwitz Rachel E.	President and CEO	Grant	137K	$0.00	$0	295K
2025-01-29	Ryali Sriram	Chief Financial Officer	Buy	17K	$1.42	$25K	17K
2024-11-20	Fischesser Ryan	VP of Finance and Controller	Grant	25K	$0.00	$0	119K
2024-02-20	Kanner Steven	Chief Scientific Officer	Grant	33K	$0.00	$0	387K
2024-02-20	Haurwitz Rachel E.	President and CEO	Grant	119K	$0.00	$0	159K
2024-02-20	Khan Ruhi Ahmad	Chief Business Officer	Grant	33K	$0.00	$0	33K
2024-02-20	MCCLUNG BARBARA G	Chief Legal Officer	Grant	33K	$0.00	$0	410K
2024-02-20	O'Byrne Jason	Chief Financial Officer	Grant	33K	$0.00	$0	59K
2024-02-06	Kanner Steven	Chief Scientific Officer	Exercise or conversion	31K	$2.69	$82K	354K
2023-06-08	Haurwitz Rachel E.	President and CEO	Exercise or conversion	10K	$2.96	$30K	40K
2023-03-20	Haurwitz Rachel E.	President and CEO	Exercise or conversion	10K	$2.96	$30K	30K
2023-01-19	Rizvi Syed Ali-aamir	Chief Medical Officer	Sell	6K	$6.31	$36K	59K
2022-12-02	Kanner Steven	Chief Scientific Officer	Exercise or conversion	21K	$2.69	$58K	323K
2022-10-06	Fischesser Ryan	VP of Finance and Controller	Exercise or conversion	3K	$4.11	$12K	116K
2022-10-06	Fischesser Ryan	VP of Finance and Controller	Sell	10K	$10.80	$108K	110K
2022-10-06	Fischesser Ryan	VP of Finance and Controller	Exercise or conversion	3K	$2.69	$8K	113K
2022-09-15	MCCLUNG BARBARA G	Chief Legal Officer	Exercise or conversion	28K	$2.69	$74K	377K
2022-09-15	MCCLUNG BARBARA G	Chief Legal Officer	Exercise or conversion	77	$2.69	$207	349K
2022-08-25	Kanner Steven	Chief Scientific Officer	Exercise or conversion	43K	$2.69	$116K	345K
2022-08-25	Kanner Steven	Chief Scientific Officer	Sell	43K	$11.22	$485K	302K
2022-08-22	Fischesser Ryan	VP of Finance and Controller	Grant	5K	$0.00	$0	120K
2022-05-13	Kanner Steven	Chief Scientific Officer	Exercise or conversion	68K	$1.81	$124K	296K
2022-05-13	Kanner Steven	Chief Scientific Officer	Exercise or conversion	6K	$2.69	$16K	302K
2022-05-09	Haurwitz Rachel E.	President and CEO	Exercise or conversion	10K	$2.96	$30K	20K
2022-05-05	Fischesser Ryan	VP of Finance and Controller	Exercise or conversion	1K	$2.69	$3K	114K
2022-05-05	Fischesser Ryan	VP of Finance and Controller	Exercise or conversion	1K	$4.11	$5K	116K
2022-03-15	Fischesser Ryan	VP of Finance and Controller	Exercise or conversion	1K	$4.11	$5K	113K
2022-03-15	Fischesser Ryan	VP of Finance and Controller	Exercise or conversion	1K	$2.69	$3K	112K
2022-03-04	Kanner Steven	Chief Scientific Officer	Exercise or conversion	2K	$4.11	$6K	228K
2022-03-04	Kanner Steven	Chief Scientific Officer	Exercise or conversion	9K	$2.69	$25K	226K
2022-02-08	O'Byrne Jason	Chief Financial Officer	Exercise or conversion	24K	$4.11	$100K	24K
2022-01-26	Haurwitz Rachel E.	President and CEO	Exercise or conversion	10K	$2.96	$30K	10K
2022-01-26	Haurwitz Rachel E.	President and CEO	Exercise or conversion	10K	$2.96	$30K	3.4M
2022-01-25	Rizvi Syed Ali-aamir	Chief Medical Officer	Grant	60K	$0.00	$0	65K
2022-01-11	Fischesser Ryan	VP of Finance and Controller	Buy	569	$2.69	$2K	102K
2022-01-11	Fischesser Ryan	VP of Finance and Controller	Buy	7K	$4.11	$28K	109K
2021-12-20	Fischesser Ryan	VP of Finance and Controller	Buy	1K	$2.69	$3K	102K
2021-12-07	MCCLUNG BARBARA G	Chief Legal Officer	Buy	6K	$2.69	$16K	349K
2021-12-07	MCCLUNG BARBARA G	Chief Legal Officer	Buy	12	$2.69	$32	343K
2021-10-20	MCCLUNG BARBARA G	Chief Legal Officer	Buy	9K	$2.69	$25K	343K
2021-10-20	MCCLUNG BARBARA G	Chief Legal Officer	Buy	43	$2.69	$116	343K
2021-10-12	Kanner Steven	Chief Scientific Officer	Buy	698	$1.81	$1K	200K
2021-10-12	Kanner Steven	Chief Scientific Officer	Buy	15K	$2.69	$39K	215K
2021-10-12	Kanner Steven	Chief Scientific Officer	Buy	100K	$1.81	$180K	200K
2021-10-11	Fischesser Ryan	VP of Finance and Controller	Buy	2K	$2.69	$5K	101K
2021-07-27	FMR LLC	Other	Conversion	771K	price not stated in the filing	not stated	771K
2021-07-27	FMR LLC	Other	Conversion	1.1M	price not stated in the filing	not stated	1.8M
2021-07-27	FMR LLC	Other	Conversion	18K	price not stated in the filing	not stated	18K
2021-07-27	FMR LLC	Other	Conversion	1.5M	price not stated in the filing	not stated	1.5M

Form 4 filings are due within two business days of the trade. Insiders sell for many reasons that say nothing about the company; open-market buys are rarer.

Planned sales (Form 144)

Newest first. JSON

3 Form 144 notices on file for CRBU worth $39K at the prices reported; 0 in the last 90 days worth $0. Latest: TIMOTHY KELLY filed on 2026-02-25 to sell 6,228 shares ($12K) from 2026-02-25.

Filed	Seller	Shares	Market value	Of outstanding	Sale from	Broker
2026-02-25	TIMOTHY KELLYOfficer	6K	$12K	0.007%	2026-02-25	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-02-25	RUHI AHMAD KHANOfficer	7K	$14K	0.007%	2026-02-24	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-02-25	BARBARA G MCCLUNGOfficer	7K	$14K	0.007%	2026-02-24	Morgan Stanley Smith Barney LLC Executive Financial Services

Large holders (13D and 13G)

One row per reporting person with its latest filing, newest first. JSON

1 holder reports 5% or more of CRBU in its latest filing, on Schedule 13G (passive). The holder is BlackRock, Inc. at 7.2% of the class (7,176,404 shares), filed 2026-07-27 for an event on 2026-06-30.

Filed	Form	Holder	Shares	Of class	Event
2026-07-27	13G	BlackRock, Inc.parent holding company	7.2M	7.2%	2026-06-30

13F holders

Tracked managers holding CRBU at their latest 13F. JSON

5 of the 30 tracked managers held CRBU at their latest 13F, $6.9M in total at quarter-end prices. Renaissance Technologies is the largest at $4.9M (0.0% of its portfolio) as of 2026-06-30. Over the prior quarter 1 added shares and 4 cut.

Fund	Quarter	Shares	Value	Of portfolio	Change in shares
Renaissance Technologies	2026-06-30	2.8M	$4.9M	0.01%	+183K
Two Sigma Investments	2026-06-30	1.0M	$1.8M	0.00%	-714K
Millennium Management	2026-06-30	51K	$90K	0.00%	-1.0M
Citadel Advisors	2026-06-30	40K	$71K	0.00%	-119K
Point72 Asset Management	2026-06-30	16K	$28K	0.00%	-172K

Only the 30 tracked managers on the funds hub; a 13F reports long positions in US listed stock at quarter end, 45 days late, and says nothing about shorts or positions sold since.

What this page is

Caribou Biosciences in the regulatory record

Regulators publish company data in separate files that never sit next to each other: FINRA's twice-monthly short interest, its daily short sale volume, the SEC's fails-to-deliver counts, and each insider's Form 4. A company page puts those series for one ticker on one URL, with planned sales, large holders, 13F holders and financials beside them, so the short position, the daily flow, the settlement fails and what insiders are doing can be read together.

Each section has its own history table, a one-line summary of the latest figures and its own JSON and CSV links, and says when its source last updated.

This page follows Caribou Biosciences (CRBU), SEC CIK 1619856, listed on Nasdaq, classified by the SEC as biological products, (no diagnostic substances). The cross-market tables live on the short interest and insider transactions hubs.

Source and updates

Short interest: FINRA consolidated short interestSource: FINRA.Twice a month, about eight business days after settlement. Latest 2026-10-15.JSON and CSV
Daily short volume: FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-11-02.JSON and CSV
Fails to deliver: SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-10-08.JSON and CSV
Planned sales: SEC EDGAR Form 144Source: SEC.New notices appear shortly after the SEC posts them; a notice is filed on or before the sale. Latest 2026-02-25.JSON and CSV
Large holders: SEC EDGAR Schedule 13D and 13GSource: SEC.New filings appear shortly after the SEC posts them. A 13D is due within five business days of crossing 5%; a 13G follows the passive schedule. Latest 2026-07-27.JSON and CSV
13F holders: SEC EDGAR Form 13F-HRSource: SEC.Quarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
Earnings dates: SEC EDGAR 8-K filings (Item 2.02)Source: SEC.Twice a day. Reported dates come from the company's 8-K filings; the next date is marked as an estimate until the 8-K arrives. Latest 2026-08-13.JSON and CSV
Insider trades: SEC EDGAR Form 4Source: SEC.New filings appear shortly after the SEC posts them; they're due two business days after the trade. Latest 2026-02-25.JSON and CSV
Company record: EDGAR filing index for CIK 1619856Ticker, name and exchange from the SEC's company list, refreshed weekly.
Rate limits: 10 requests a minute without a key, 30 with a free key from a free account.

How to read it

Read the position against the flow: rising short interest with a high daily short share is new shorting; rising short interest with a normal short share is old shorts holding on.
Insider buys next to a large short position are rare and stand out; insider sells next to one are common and mean little.
Fails to deliver matter relative to the float, not in absolute shares; a million failed shares in a mega cap is noise.

Analysis of what the data shows, not advice. XOOMAR does not recommend buying, selling or holding anything.

Other companies the SEC classifies as biological products, (no diagnostic substances)

Other company pages

Datasets

Frequently Asked Questions

How much of CRBU is sold short?

12,554,864 shares were held short at the 2026-10-15 settlement, 1.5 days of average volume. FINRA publishes the next count about eight business days after the 15th and the last business day of the month.

What is CRBU's daily short volume?

On 2026-11-02, 694,703 of the 1,319,450 CRBU shares reported to FINRA were sold short, 52.6% of the day's reported volume. Short volume is a flow for one day, not a position.

Does CRBU have fails to deliver?

The SEC's latest file shows 74,206 CRBU shares failed to deliver at settlement 2026-10-08. Fails are reported per settlement date and published twice a month with a lag.

Are CRBU insiders buying or selling?

No open-market insider trades were reported for CRBU in the last 90 days. The most recent filings are listed below. Latest filing: Kelly Timothy P (Chief Technology Officer) on 2026-02-25.

Have CRBU insiders filed to sell?

3 Form 144 notices on file for CRBU worth $39K at the prices reported; 0 in the last 90 days worth $0. Latest: TIMOTHY KELLY filed on 2026-02-25 to sell 6,228 shares ($12K) from 2026-02-25.

Who owns 5% or more of CRBU?

Which tracked 13F managers own CRBU?

5 of the 30 tracked 13F managers held CRBU shares at their latest filing, $6.9M in all. The largest: Renaissance Technologies (2.8M shares, $4.9M), Two Sigma Investments (1.0M shares, $1.8M), Izzy Englander's Millennium Management (51K shares, $90K), Ken Griffin's Citadel Advisors (40K shares, $71K), Steve Cohen's Point72 Asset Management (16K shares, $28K).

Data on this page is provided for informational purposes only and is not financial advice. See our editorial policy.