Short interest // FINRA, biweekly, dated

MBIO short interest

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Mustang Bio, Inc. Common Stock

0.87% of MBIO’s shares outstanding is sold short

58,855 shares short / 6,735,810 shares outstanding (share count as of 2026-09-30, 10-Q).

“Low” describes how crowded the short position is, not where the stock goes next. Percent of shares outstanding, not percent of float; where filings allow it, the float version appears below as a floor.

As of the 2026-10-15 settlement, which is 26 days ago. FINRA publishes twice a month on the seventh business day after settlement, so this cycle was published around 2026-10-26 and the next is expected around 2026-11-10. No free source anywhere has anything fresher, including sites that display this number next to a live price.

Shares sold short	58,855 ⊙ EVIDENCE — filed/published fact SourceFINRA consolidated short interest FieldcurrentShortPositionQuantity As of2026-10-15 settlement HowFile shrt20261015.csv in FINRA's catalog (posted ~7 business days after settlement). Open the source document →
Prior settlement	52,680
Change	+11.7%
Days to coverShares short divided by average daily volume, both FINRA figures.	1.08 ⊙ INFERENCE — derived by arithmetic SourceFINRA consolidated short interest FieldcurrentShortPositionQuantity ÷ averageDailyVolumeQuantity As of2026-10-15 settlement HowComputed from FINRA’s two published operands. FINRA’s own daysToCoverQuantity field floors at 1.00 and is not used. Open the source document →
Average daily volume (FINRA, the days-to-cover denominator)	54,465
Exchange	Nasdaq (SmallCap)
Reg SHO threshold listPersistent settlement failures under Reg SHO Rule 203. A delivery-failure list, not a “naked shorting” list.	Not on the list (2026-11-09)
Short interest, % of shares outstandingPercent of shares outstanding. Not percent of float, and the two are not the same number.	0.87%
Shares outstandingfrom filings, as of 2026-09-30	6,735,810

Short interest history

77 settlements on record, oldest 2023-08-15. Biweekly points, from FINRA’s own archive.

Dashed line at the 15 September 2026 settlement: FINRA began quoting every field of its short interest file. What it did to this history, and what we did

Settlement	Shares short	Change	% of shares out	Days to cover	Close, USD	Value short, USD
2026-10-15	58,855	+11.7%	no share count within 200 days	1.08	0.39	22,724
2026-09-30	52,680	-10.0%	no share count within 200 days	1.69	0.46	24,391
2026-09-15	58,509	+6.3%	no share count within 200 days	2.49	0.50	29,459
2026-08-31	55,039	+4.7%	no share count within 200 days	3.55	0.54	29,583
2026-08-14	52,568	-4.7%	no share count within 200 days	1.43	0.59	31,199
2026-07-31	55,145	-9.4%	no share count within 200 days	1.92	0.57	31,444
2026-07-15	60,867	-40.6%	no share count within 200 days	1.45	0.63	38,468
2026-06-30	102,440	-32.0%	no share count within 200 days	2.07	0.70	71,913
2026-06-15	150,627	+176.0%	no share count within 200 days	0.27	0.74	111,178
2026-05-29	54,570	+1.8%	no share count within 200 days	1.20	0.67	36,567
2026-05-15	53,594	-25.7%	no share count within 200 days	1.31	0.61	32,451
2026-04-30	72,110	-28.7%	no share count within 200 days	1.71	0.74	53,434

Show the other 65 settlements, back to 2023-08-15

Settlement	Shares short	Change	% of shares out	Days to cover	Close, USD	Value short, USD
2026-04-15	101,076	-19.4%	no share count within 200 days	2.91	0.76	76,939
2026-03-31	125,433	+48.1%	no share count within 200 days	3.31	0.73	91,315
2026-03-13	84,718	-36.8%	no share count within 200 days	2.33	0.94	79,804
2026-02-27	133,993	-39.2%	no share count within 200 days	3.58	1.01	135,333
2026-02-13	220,214	+405.2%	no share count within 200 days	0.29	0.87	192,489
2026-01-30	43,589	+8.6%	no share count within 200 days	0.92	0.96	42,063
2026-01-15	40,129	-22.1%	no share count within 200 days	0.64	1.05	42,135
2025-12-31	51,498	-12.3%	no share count within 200 days	0.51	0.98	50,520
2025-12-15	58,750	-32.3%	no share count within 200 days	0.74	1.13	66,388
2025-11-28	86,746	+22.2%	no share count within 200 days	0.72	1.41	122,312
2025-11-14	70,984	+16.0%	no share count within 200 days	0.80	1.22	86,600
2025-10-31	61,181	-10.6%	no share count within 200 days	0.62	1.45	88,712
2025-10-15	68,415	+12.6%	no share count within 200 days	0.48	1.67	114,253
2025-09-30	60,750	-26.5%	no share count within 200 days	0.61	1.52	92,340
2025-09-15	82,705	-43.5%	no share count within 200 days	0.62	1.58	130,674
2025-08-29	146,262	-17.6%	no share count within 200 days	1.41	1.51	220,856
2025-08-15	177,446	+31.0%	no share count within 200 days	0.93	1.77	314,079
2025-07-31	135,488	-63.3%	no share count within 200 days	0.37	1.53	207,297
2025-07-15	369,015	+33446.8%	no share count within 200 days	0.01	2.39	881,946
2025-06-30	1,100	-71.4%	no share count within 200 days	0.01	0.96	1,051
2025-06-13	3,845	-96.0%	no share count within 200 days	0.07	1.17	4,499
2025-05-30	97,080	+65.0%	no share count within 200 days	0.75	1.31	127,175
2025-05-15	58,835	-70.5%	no share count within 200 days	0.43	1.13	66,484
2025-04-30	199,322	+228.2%	no share count within 200 days	0.10	1.09	217,261
2025-04-15	60,740	+0.6%	no share count within 200 days	0.76	1.36	82,606
2025-03-31	60,389	+37.2%	no share count within 200 days	1.18	1.25	75,486
2025-03-14	44,005	-52.0%	no share count within 200 days	0.42	1.41	62,047
2025-02-28	91,738	-22.4%	no share count within 200 days	0.45	2.00	183,476
2025-02-14	118,220	-7.0%	no share count within 200 days	0.58	2.80	331,016
2025-01-31	127,127	-93.1%	no share count within 200 days	0.22	4.32	549,189
2025-01-15	1,850,815	+423.6%	no share count within 200 days	0.04	0.13	232,462
2024-12-31	353,454	-4.8%	no share count within 200 days	0.35	0.18	62,561
2024-12-13	371,097	+46.5%	no share count within 200 days	0.64	0.19	71,733
2024-11-29	253,361	-40.4%	no share count within 200 days	0.48	0.20	50,546
2024-11-15	424,910	-20.5%	no share count within 200 days	0.32	0.23	97,007
2024-10-31	534,213	+6.4%	no share count within 200 days	0.08	0.28	149,580
2024-10-15	501,966	+31.4%	no share count within 200 days	1.82	0.22	109,579
2024-09-30	382,144	-41.8%	no share count within 200 days	0.68	0.24	89,918
2024-09-13	656,396	+1.3%	no share count within 200 days	1.30	0.27	177,227
2024-08-30	647,744	-59.9%	no share count within 200 days	0.64	0.28	182,146
2024-08-15	1,616,915	+49.6%	no share count within 200 days	1.84	0.38	606,828
2024-07-31	1,080,950	-14.7%	no share count within 200 days	0.31	0.33	361,145
2024-07-15	1,267,933	-57.1%	no share count within 200 days	0.29	0.40	502,101
2024-06-28	2,956,951	+334.2%	no share count within 200 days	0.02	before stored bars	no close to value it
2024-06-14	680,992	-70.8%	no share count within 200 days	0.27	before stored bars	no close to value it
2024-05-31	2,331,326	+843.3%	no share count within 200 days	0.15	before stored bars	no close to value it
2024-05-15	247,158	+200.9%	no share count within 200 days	1.63	before stored bars	no close to value it
2024-04-30	82,150	-39.8%	no share count within 200 days	0.30	before stored bars	no close to value it
2024-04-15	136,523	-23.3%	no share count within 200 days	0.44	before stored bars	no close to value it
2024-03-28	177,977	-54.3%	no share count within 200 days	1.01	before stored bars	no close to value it
2024-03-15	389,026	+829.1%	no share count within 200 days	0.76	before stored bars	no close to value it
2024-02-29	41,871	-1.9%	no share count within 200 days	1.36	before stored bars	no close to value it
2024-02-15	42,676	-15.7%	no share count within 200 days	1.26	before stored bars	no close to value it
2024-01-31	50,625	+58.6%	no share count within 200 days	1.51	before stored bars	no close to value it
2024-01-12	31,924	-52.9%	no share count within 200 days	0.48	before stored bars	no close to value it
2023-12-29	67,843	-18.2%	no share count within 200 days	0.67	before stored bars	no close to value it
2023-12-15	82,898	-4.4%	no share count within 200 days	1.23	before stored bars	no close to value it
2023-11-30	86,746	+15.8%	no share count within 200 days	1.42	before stored bars	no close to value it
2023-11-15	74,896	-59.9%	no share count within 200 days	1.05	before stored bars	no close to value it
2023-10-31	186,742	+571.1%	no share count within 200 days	0.71	before stored bars	no close to value it
2023-10-13	27,825	-53.0%	no share count within 200 days	1.37	before stored bars	no close to value it
2023-09-29	59,241	+167.4%	no share count within 200 days	3.01	before stored bars	no close to value it
2023-09-15	22,157	-60.0%	no share count within 200 days	1.03	before stored bars	no close to value it
2023-08-31	55,377	+59.9%	no share count within 200 days	1.38	before stored bars	no close to value it
2023-08-15	34,626	no prior settlement	no share count within 200 days	1.37	before stored bars	no close to value it

Change is against the settlement before it, and is left out where one is missing from the archive. Percent of shares outstanding divides by the filed share count dated nearest each settlement, within 200 days, so it moves when the share count does; it is not percent of float. Close and value short (shares short times that day’s close, both as traded) come from our stored daily bars, which begin 2024-07-01; earlier settlements show none rather than a figure from another source. Nothing here is split-adjusted, so a split appears as the step it was.

Different measurement // daily, and not a position

Daily short volume

This is not the number above. Short interest is the position still held short, reported twice a month. Short volume is the share of a single day’s trading that was marked as a sell-short order, published daily. Most of it is market makers hedging and closing within the same session, so a stock printing a high figure here is not that percentage sold short.

Latest session (2026-11-09)

13.9%

Average, last 10 sessions

25.1%

2026-11-0913.9%

2026-11-067.0%

2026-11-0529.9%

2026-11-0417.2%

2026-11-031.2%

2026-11-0234.1%

2026-10-3030.7%

2026-10-2956.8%

2026-10-2848.5%

2026-10-2712.0%

FINRA Reg SHO consolidated daily file. Sessions with no row for MBIO are omitted rather than shown as zero.

Price context // daily bars, not short data

Where the price sits

Session of 2026-11-09, from 276 sessions of daily bars. These are price figures, not short figures, and they update daily rather than twice a month.

Close	$0.39
Volume, latest session	18,911
Volume vs averageAgainst its own 50-session average of 32,127, same series on both sides	0.59x
% from 52-week high ($1.43)	-72.6%
% from 52-week low ($0.35)	+11.7%
52-week performance	-68.2%
% from 50-day average ($0.45)	-13.7%
% from 200-day average ($0.67)	-41.4%
RSI, 14-dayWilder’s construction, so it matches what charting platforms print	42.6

Why there is no “% of float” here

Percent of float is the number the paid trackers lead with, and it is the one number in this category that cannot be published honestly for free. There is no free float share count: the SEC’s XBRL concept for float does not exist, and the closest one, public float, is measured in dollars and is filed once a year with the annual report. For Apple it currently reads as of March 2025, sixteen months ago.

So a free site showing percent of float is doing one of two things: quietly substituting shares outstanding, which for a heavily insider-held small company is a wildly different number, or republishing a commercial estimate it licensed. We publish the percentage that filed data supports, label it as percent of shares outstanding, and where insider Form 4 filings allow it we publish percent of float as an explicit floor: subtracting only filed direct insider holdings from shares outstanding gives a ceiling on float, so the division gives a number the true percentage can only exceed. What we will not do is print a bare “% of float” built on someone else’s estimate. Where a figure is measured, this site says what it was measured against. Read the methodology.

What days to cover means

Open short interest divided by average daily trading volume: roughly how many full sessions of normal volume it would take for every short position to be bought back. FINRA computes it per security at each settlement and we pass their figure through. This matters more than it sounds, because sites that compute their own pick their own volume window and rarely say which, so the same stock shows materially different values depending on where you look.

High short interest and high days to cover describe fuel, not ignition. They say a crowded position exists; they say nothing about whether it unwinds, and heavily shorted stocks frequently keep falling. Educational information, not investment advice.

FINRA is the owner and source of this short interest and short sale volume data. Free on every plan; not for redistribution.

MBIO short interest FAQ

How old is this MBIO short interest figure?

It is the 2026-10-15 settlement, which is 26 days ago. FINRA collects short interest twice a month and publishes on the seventh business day after each settlement date, so this was published around 2026-10-26 and the next cycle is expected around 2026-11-10. There is no fresher short interest available anywhere for free, including from tools that display it next to a live price.

Why does this show percent of shares outstanding rather than percent of float?

Because float share counts are not published by any free source. The SEC XBRL concept for float does not exist, and the nearest one is measured in dollars and comes only from the annual report. Every free site showing a float percentage is republishing a commercial estimate. We publish the percentage we can compute from filed data and label it for what it is, rather than passing shares outstanding off as float.

Where does days to cover come from?

Shares short divided by average daily volume, using FINRA’s own two published figures. We do not use FINRA’s own days-to-cover field, because it is floored at 1.00: across the current file, 7,869 securities, over a third of the market, are published at exactly 1.00 and nearly all of them are genuinely below it. One stock with a true ratio of 0.03 is published as 1.00. Sites that instead invent their own average-volume window produce a different problem, which is why the operands here are both FINRA’s.

Is high short interest a buy signal?

No. High short interest is frequently the market pricing real problems, and many heavily shorted stocks keep falling. This page measures positioning. It makes no recommendation.

Keep going: the full MBIO workspace · short squeeze screener · MBIO dilution profile · MBIO off-exchange (ATS) volume · what short interest means · methodology