Pacific Biosciences Of California (PACB)

Pacific Biosciences Of California 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 laboratory analytical instruments.

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47.2M

Short interest

settlement 2026-09-30

3.0

Days to cover

-7.5 days vs prior

40.5%

Short share of volume

2026-10-09

4,275

Fails to deliver

settlement 2026-09-08

Wed 4 Nov

Next earnings

estimated date

-$2.1M

Insider flow, 90 days

0 buys, 2 sells

As of 2026-10-09.

Short interest

FINRA, twice a month. The newest 24 settlements in the table, 48 in the chart. JSON

As of 30 September 2026, short interest in PACB is 47,224,448 shares, down 2,354,322 shares over the last month. Over the last 48 readings it ranged from 32,511,384 shares (31 October 2025) to 66,690,554 shares (14 February 2025). At the reported average volume of 15.9M shares a day that is 3.0 days to cover.

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Settlement	Shares short	Change	Avg daily volume	Days to cover
2026-09-30	47,224,448	-3.4%	15,907,977	2.97
2026-09-15	48,892,225	-1.4%	4,660,230	10.49
2026-08-31	49,578,770	-7.2%	7,342,641	6.75
2026-08-14	53,412,027	+9.0%	8,056,891	6.63
2026-07-31	49,004,841	+6.0%	6,666,706	7.35
2026-07-15	46,237,636	-2.6%	4,638,329	9.97
2026-06-30	47,490,204	-21.6%	7,291,153	6.51
2026-06-15	60,560,138	+24.3%	5,954,109	10.17
2026-05-29	48,707,384	-18.7%	5,684,330	8.57
2026-05-15	59,926,798	+27.3%	6,645,578	9.02
2026-04-30	47,090,593	+1.6%	6,688,960	7.04
2026-04-15	46,364,406	+1.6%	5,505,784	8.42
2026-03-31	45,631,632	+10.3%	5,428,096	8.41
2026-03-13	41,388,621	+8.4%	6,304,987	6.56
2026-02-27	38,191,242	-1.9%	5,352,300	7.14
2026-02-13	38,916,811	+9.3%	7,386,819	5.27
2026-01-30	35,591,593	+1.4%	8,377,033	4.25
2026-01-15	35,091,747	+3.2%	8,781,846	4.00
2025-12-31	34,003,835	-0.8%	6,403,082	5.31
2025-12-15	34,259,532	+0.6%	6,286,336	5.45
2025-11-28	34,042,917	+1.4%	11,064,220	3.08
2025-11-14	33,569,699	+3.3%	9,267,258	3.62
2025-10-31	32,511,384	-5.8%	11,362,122	2.86
2025-10-15	34,508,178	-9.1%	8,397,808	4.11

Daily short volume

FINRA Reg SHO, the last 30 sessions. JSON

As of 9 October 2026, the short share of PACB volume is 40.5%, down 2.2 points over the last five sessions. Over the last 30 readings it ranged from 25.6% (28 September 2026) to 54.9% (23 September 2026). The latest reading is 2.4 points below the 30-session average of 42.9%, on 5.5M shares reported.

Date	Short volume	Total volume	Short share	Exempt
2026-10-09	2.2M	5.5M	40.5%	239,946
2026-10-08	3.3M	9.5M	34.8%	288,031
2026-10-07	4.4M	8.8M	49.9%	326,520
2026-10-06	12.3M	24.0M	51.1%	590,872
2026-10-05	4.4M	12.6M	35.1%	608
2026-10-02	5.0M	11.7M	42.8%	22,668
2026-10-01	5.9M	12.5M	47.5%	16,111
2026-09-30	14.8M	38.2M	38.8%	65,082
2026-09-29	2.5M	7.3M	34.2%	6,580
2026-09-28	2.3M	9.0M	25.6%	23,896
2026-09-25	1.5M	4.1M	37.3%	75,961
2026-09-24	1.9M	4.6M	39.9%	1,070
2026-09-23	1.3M	2.3M	54.9%	635
2026-09-22	1.1M	3.7M	29.6%	3,642
2026-09-21	1.0M	2.7M	38.4%	37,952
2026-09-18	699K	1.6M	45.1%	870
2026-09-17	1.7M	3.2M	53.7%	115,102
2026-09-16	860K	1.9M	45.1%	15,086
2026-09-15	1.3M	2.7M	45.8%	28,103
2026-09-14	934K	2.4M	38.7%	253
2026-09-11	619K	1.6M	37.8%	58
2026-09-10	1.4M	2.6M	54.0%	4,902
2026-09-09	942K	2.0M	46.3%	0
2026-09-08	866K	1.9M	45.0%	5,226
2026-09-04	587K	1.2M	50.1%	4,966
2026-09-03	1.3M	2.8M	45.4%	4,374
2026-09-02	1.0M	2.2M	48.4%	0
2026-09-01	1.8M	3.8M	46.9%	83,401
2026-08-31	1.6M	3.8M	42.3%	90,771
2026-08-28	1.2M	2.8M	41.7%	24,444

Fails to deliver

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

As of 8 September 2026, the fails-to-deliver balance in PACB is 4,275 shares, up 4,195 shares over the last settlement date. Over the last 30 readings it ranged from 70 shares (7 August 2026) to 906,304 shares (6 August 2026). The latest reading sits at the bottom of that range.

Settlement	Shares failed	Price	Value
2026-09-08	4,275	$1.35	$6K
2026-08-27	80	$1.56	$125
2026-08-26	56,521	$1.52	$86K
2026-08-25	2,314	$1.28	$3K
2026-08-24	16,495	$1.35	$22K
2026-08-20	7,038	$1.27	$9K
2026-08-18	55,011	$1.21	$67K
2026-08-17	8,674	$1.15	$10K
2026-08-13	152,647	$1.11	$169K
2026-08-07	70	$1.17	$82
2026-08-06	906,304	$1.30	$1.2M
2026-07-31	531	$1.48	$786
2026-07-30	1,270	$1.40	$2K
2026-07-23	56,994	$1.38	$79K
2026-07-20	141,083	$1.44	$203K
2026-07-13	7,744	$1.56	$12K
2026-07-07	103	$1.66	$171
2026-07-06	78,369	$1.68	$132K
2026-07-02	43,723	$1.74	$76K
2026-06-30	493,358	$1.73	$854K
2026-06-29	286,839	$1.65	$473K
2026-06-17	7,125	$1.35	$10K
2026-06-15	601,723	$1.31	$788K
2026-06-11	25,663	$1.37	$35K
2026-06-10	10,648	$1.37	$15K
2026-06-08	42,373	$1.45	$61K
2026-06-05	655	$1.63	$1K
2026-06-04	44,380	$1.58	$70K
2026-06-03	138,780	$1.58	$219K
2026-05-29	157,785	$1.47	$232K

Insider trades

SEC Form 4, newest first, 50 of 100 shown. JSON

Insiders at PACB reported 2 open-market sells worth $2.1M in the last 90 days and no open-market buys. Latest filing: Gibson James R II (See Remarks) on 2026-10-06.

Date	Insider	Title	Type	Shares	Price	Value	Owned after
2026-10-06	Gibson James R II	See Remarks	Sell	662K	$3.11	$2.1M	1.1M
2026-10-06	Gibson James R II	See Remarks	Option exercise	500K	$1.18	$590K	1.7M
2026-08-17	Van Oene Mark	See Remarks	Sell	27K	$1.13	$30K	2.7M
2026-08-10	Van Oene Mark	See Remarks	Grant	489K	$0.00	$0	2.7M
2026-04-08	Gibson Christopher	Director	Grant	57K	$0.00	$0	111K
2026-04-01	Gibson James R II	See Remarks	Sell	88K	$1.37	$121K	1.2M
2026-03-03	Van Oene Mark	See Remarks	Sell	7K	$1.51	$10K	2.2M
2026-03-03	HENRY CHRISTIAN O	See Remarks	Sell	12K	$1.51	$19K	3.6M
2026-03-03	Farmer Michele	See Remarks	Sell	3K	$1.51	$5K	306K
2026-03-03	Gibson Christopher	Director	Grant	54K	$0.00	$0	54K
2026-02-27	Van Oene Mark	See Remarks	Grant	500K	$0.00	$0	2.2M
2026-02-27	HENRY CHRISTIAN O	See Remarks	Grant	921K	$0.00	$0	3.6M
2026-02-27	Gibson James R II	See Remarks	Grant	334K	$0.00	$0	1.3M
2026-02-27	Farmer Michele	See Remarks	Grant	90K	$0.00	$0	309K
2026-02-18	Van Oene Mark	See Remarks	Sell	55K	$1.63	$90K	1.7M
2026-02-18	HENRY CHRISTIAN O	See Remarks	Sell	141K	$1.63	$229K	2.7M
2026-02-18	Farmer Michele	See Remarks	Sell	15K	$1.63	$24K	219K
2026-02-17	Van Oene Mark	See Remarks	Sell	130K	$1.58	$205K	1.8M
2026-02-17	HENRY CHRISTIAN O	See Remarks	Sell	332K	$1.58	$523K	2.8M
2026-02-17	Farmer Michele	See Remarks	Sell	35K	$1.58	$55K	234K
2025-08-18	Van Oene Mark	See Remarks	Sell	27K	$1.31	$35K	1.9M
2025-05-19	Farmer Michele	See Remarks	Sell	5K	$1.00	$5K	269K
2025-03-31	Gibson James R II	See Remarks	Grant	1.0M	$0.00	$0	1.0M
2025-03-19	HENRY CHRISTIAN O	See Remarks	Grant	921K	$0.00	$0	3.1M
2025-03-19	Van Oene Mark	See Remarks	Grant	449K	$0.00	$0	1.9M
2025-03-19	Farmer Michele	See Remarks	Grant	90K	$0.00	$0	274K
2025-03-03	Farmer Michele	See Remarks	Sell	3K	$1.41	$4K	185K
2025-03-03	Van Oene Mark	See Remarks	Sell	6K	$1.41	$9K	1.5M
2025-03-03	HENRY CHRISTIAN O	See Remarks	Sell	12K	$1.41	$18K	2.2M
2025-02-18	HENRY CHRISTIAN O	See Remarks	Sell	260K	$1.88	$489K	2.2M
2025-02-18	Van Oene Mark	See Remarks	Sell	101K	$1.88	$189K	1.5M
2025-02-18	Farmer Michele	See Remarks	Sell	24K	$1.88	$46K	188K
2025-01-30	Smith Christopher M	Director	Grant	54K	$0.00	$0	54K
2025-01-10	Van Oene Mark	See Remarks	Sell	34K	$2.03	$70K	1.6M
2024-09-30	Kim Susan G.	See Remarks	Sell	20K	$1.72	$34K	696K
2024-09-16	HENRY CHRISTIAN O	See Remarks	Sell	99K	$1.75	$173K	2.5M
2024-08-19	Eidel Jeff	See Remarks	Sell	27K	$1.59	$43K	870K
2024-08-16	Van Oene Mark	See Remarks	Sell	38K	$1.66	$63K	1.6M
2024-06-18	Ericson William W.	Director	Grant	23K	$0.00	$0	42K
2024-06-18	LIVINGSTON RANDALL S	Director	Grant	23K	$0.00	$0	23K
2024-06-18	Meline David W	Director	Grant	17K	$0.00	$0	57K
2024-06-18	MILLIGAN JOHN F	Director	Grant	23K	$0.00	$0	133K
2024-06-18	MOHR MARSHALL	Director	Grant	23K	$0.00	$0	133K
2024-06-18	ORDONEZ KATHY	Director	Grant	23K	$0.00	$0	403K
2024-06-18	Shapiro Lucy	Director	Grant	23K	$0.00	$0	23K
2024-06-18	Valantine Hannah	Director	Grant	23K	$0.00	$0	23K
2024-05-20	Farmer Michele	See Remarks	Sell	5K	$2.03	$11K	212K
2024-03-15	ORDONEZ KATHY	Director	Option exercise	325K	$2.90	$941K	343K
2024-03-15	ORDONEZ KATHY	Director	Option exercise	37K	$2.63	$98K	380K
2024-03-06	Meline David W	Director	Buy	40K	$4.40	$176K	40K

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

7 Form 144 notices on file for PACB worth $3.5M at the prices reported; 2 in the last 90 days worth $1.9M. Latest: Jim Gibson filed on 2026-10-06 to sell 661,815 shares ($1.9M) from 2026-10-06.

Filed	Seller	Shares	Market value	Of outstanding	Sale from	Broker
2026-10-06	Jim GibsonOfficer	662K	$1.9M	0.213%	2026-10-06	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-08-17	MARK VAN OENEOfficer	27K	$31K	0.009%	2026-08-17	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-04-01	JAMES GIBSONOfficer	88K	$121K	0.029%	2026-04-01	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-03-03	MARK D. VAN OENEOfficer	7K	$10K	0.002%	2026-03-03	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-03-03	CHRISTIAN HENRYOfficer	12K	$19K	0.004%	2026-03-03	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-02-17	MARK VAN OENEOfficer	304K	$479K	0.101%	2026-02-17	Morgan Stanley Smith Barney LLC Executive Financial Services
2026-02-17	CHRISTIAN HENRYOfficer	606K	$956K	0.201%	2026-02-17	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

2 holders report 5% or more of PACB in their latest filing, all on Schedule 13G (passive). The largest reported stake is ARK Investment Management LLC at 9.6% of the class (29,781,416 shares), filed 2026-08-14 for an event on 2026-06-30.

Filed	Form	Holder	Shares	Of class	Event
2026-08-14	13G/Ano. 7	ARK Investment Management LLCinvestment adviser	29.8M	9.6%	2026-06-30
2026-08-14	13G/Ano. 7	Catherine D. Woodparent holding company, individual	29.8M	9.6%	2026-06-30
2026-03-27	13G/Ano. 4	The Vanguard Groupinvestment adviser	0	0.0%	2026-03-13
2025-11-14	13G/Ano. 5	Gregory Boyd Pennerindividual	8.5M	2.8%	2025-09-30
2025-11-14	13G/Ano. 5	Madrone Opportunity Fund, L.P.partnership	5.0M	1.7%	2025-09-30
2025-11-14	13G/Ano. 5	Madrone Capital Partners, LLCother entity	5.0M	1.7%	2025-09-30
2025-11-14	13G/Ano. 5	Jameson J. McJunkinindividual	5.0M	1.7%	2025-09-30
2025-11-14	13G/Ano. 5	Thomas Pattersonindividual	5.0M	1.7%	2025-09-30
2025-11-14	13G/Ano. 5	Shimoda Holdings, LLCother entity	3.5M	1.2%	2025-09-30

13F holders

Tracked managers holding PACB at their latest 13F. JSON

9 of the 30 tracked managers held PACB at their latest 13F, $87.7M in total at quarter-end prices. ARK Investment Management is the largest at $50.0M (0.3% of its portfolio) as of 2026-06-30. Over the prior quarter 6 added shares and 3 cut.

Fund	Quarter	Shares	Value	Of portfolio	Change in shares
ARK Investment Management	2026-06-30	29.8M	$50.0M	0.32%	-6.5M
Point72 Asset Management	2026-06-30	4.8M	$8.0M	0.01%	+4.5M
Two Sigma Investments	2026-06-30	4.2M	$7.1M	0.01%	+733K
D. E. Shaw & Co.	2026-06-30	4.2M	$7.1M	0.00%	+571K
Millennium Management	2026-06-30	4.0M	$6.7M	0.00%	-930K
Citadel Advisors	2026-06-30	2.8M	$4.8M	0.00%	+1.3M
AQR Capital Management	2026-06-30	1.3M	$2.2M	0.00%	+537K
Renaissance Technologies	2026-06-30	966K	$1.6M	0.00%	-1.5M
Bridgewater Associates	2026-06-30	103K	$173K	0.00%	new

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

Pacific Biosciences Of California 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 Pacific Biosciences Of California (PACB), SEC CIK 1299130, listed on Nasdaq, classified by the SEC as laboratory analytical instruments. 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 2026-09-30.JSON and CSV
Daily short volume: FINRA Reg SHO daily filesSource: FINRA.Every trading day, the morning after FINRA posts it. Latest 2026-10-09.JSON and CSV
Fails to deliver: SEC fails-to-deliver dataSource: SEC.Twice a month, a few weeks after the half month ends. Latest 2026-09-08.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 2026-10-06.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 2026-08-14.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 2026-08-05.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 2026-10-06.JSON and CSV
Company record: EDGAR filing index for CIK 1299130Ticker, 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 laboratory analytical instruments

Other company pages

Datasets

Frequently Asked Questions

How much of PACB is sold short?

47,224,448 shares were held short at the 2026-09-30 settlement, 3.0 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 PACB's daily short volume?

On 2026-10-09, 2,223,648 of the 5,488,518 PACB shares reported to FINRA were sold short, 40.5% of the day's reported volume. Short volume is a flow for one day, not a position.

Does PACB have fails to deliver?

The SEC's latest file shows 4,275 PACB shares failed to deliver at settlement 2026-09-08. Fails are reported per settlement date and published twice a month with a lag.

Are PACB insiders buying or selling?

Insiders at PACB reported 2 open-market sells worth $2.1M in the last 90 days and no open-market buys. Latest filing: Gibson James R II (See Remarks) on 2026-10-06.

Have PACB insiders filed to sell?

7 Form 144 notices on file for PACB worth $3.5M at the prices reported; 2 in the last 90 days worth $1.9M. Latest: Jim Gibson filed on 2026-10-06 to sell 661,815 shares ($1.9M) from 2026-10-06.

Who owns 5% or more of PACB?

Which tracked 13F managers own PACB?

9 of the 30 tracked 13F managers held PACB shares at their latest filing, $87.7M in all. The largest: Cathie Wood's ARK Investment Management (29.8M shares, $50.0M), Steve Cohen's Point72 Asset Management (4.8M shares, $8.0M), Two Sigma Investments (4.2M shares, $7.1M), D. E. Shaw & Co. (4.2M shares, $7.1M), Izzy Englander's Millennium Management (4.0M shares, $6.7M), Ken Griffin's Citadel Advisors (2.8M shares, $4.8M). The table above lists all 9.

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