XOOMAR

TANDEM DIABETES CARE INC (TNDM)

Every FINRA and SEC series the site collects for TANDEM DIABETES CARE INC: short interest with days to cover, daily short sale volume, fails to deliver and Form 4 insider trades. Listed on Nasdaq, classified by the SEC as surgical & medical instruments & apparatus.

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11.8M

Short interest

settlement 2026-08-31

8.2

Days to cover

+11.0% vs prior

70.0%

Short share of volume

2026-09-17

499

Fails to deliver

settlement 2026-08-24

Thu 5 Nov

Next earnings

estimated; last year 2025-11-06

$0

Insider flow, 90 days

0 buys, 0 sells

As of 2026-09-17.

Short interest

FINRA, twice a month; the last 12 months shown, all 48 settlements in the JSON

As of 31 August 2026, short interest in TNDM is 11,753,819 shares, up 511,275 shares over the last month. Over the last 48 readings it ranged from 5,769,176 shares (15 August 2025) to 13,115,208 shares (15 July 2026). At the reported average volume of 1.4M shares a day that is 8.2 days to cover, elevated.

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SettlementShares shortChangeAvg daily volumeDays to cover
2026-08-3111,753,819+11.0%1,438,8768.17
2026-08-1410,585,732-5.8%2,723,4483.89
2026-07-3111,242,544-14.3%1,708,5626.58
2026-07-1513,115,208+3.0%1,501,6858.73
2026-06-3012,731,073+17.3%2,264,3845.62
2026-06-1510,854,250-7.9%2,664,9034.07
2026-05-2911,788,786+9.1%2,837,9544.15
2026-05-1510,801,432+11.1%3,219,9243.35
2026-04-309,723,853+0.8%1,575,9136.17
2026-04-159,643,357-8.4%1,489,6726.47
2026-03-3110,531,890-0.1%2,083,5575.05
2026-03-1310,547,769+8.0%1,759,3676.00
2026-02-279,763,559+9.0%4,262,4942.29
2026-02-138,960,466+0.3%977,0599.17
2026-01-308,934,137-0.8%1,361,7816.56
2026-01-159,004,559+5.4%1,327,7406.78
2025-12-318,544,303+4.5%1,275,7186.70
2025-12-158,176,917-6.6%1,772,1364.61
2025-11-288,753,315-0.4%2,801,8033.12
2025-11-148,787,092+0.2%2,842,2243.09
2025-10-318,766,366-5.1%1,477,8025.93
2025-10-159,237,943-0.4%2,085,2044.43
2025-09-309,278,427+16.9%1,852,9625.01
2025-09-157,933,381+19.3%1,646,2504.82

Daily short volume

FINRA Reg SHO, last 60 sessions. JSON

As of 17 September 2026, the short share of TNDM volume is 70.0%, up 13.8 points over the last five sessions. Over the last 52 readings it ranged from 31.1% (6 August 2026) to 82.5% (24 July 2026). The latest reading is 16.1 points above the 30-session average of 54.0%, on 768K shares reported.

DateShort volumeTotal volumeShort shareExempt
2026-09-17538K768K70.0%0
2026-09-16768K1.5M52.3%988
2026-09-15448K971K46.1%0
2026-09-14363K768K47.3%10
2026-09-11503K879K57.2%592
2026-09-10327K582K56.2%138
2026-09-09433K642K67.4%11
2026-09-08344K769K44.7%0
2026-09-04246K600K41.1%8
2026-09-03249K620K40.2%0
2026-09-02219K386K56.6%2,708
2026-09-01220K315K69.8%801
2026-08-31268K635K42.2%286
2026-08-28279K386K72.4%5
2026-08-27257K425K60.5%0
2026-08-26304K513K59.3%156
2026-08-25274K489K56.1%4,580
2026-08-24192K328K58.6%11
2026-08-21479K988K48.4%0
2026-08-20338K752K44.9%5
2026-08-19367K802K45.7%0
2026-08-18486K1.3M38.6%643
2026-08-17385K569K67.6%962
2026-08-14548K877K62.5%69,938
2026-08-13301K586K51.4%4,321
2026-08-12395K642K61.5%1,506
2026-08-11464K773K60.0%4,962
2026-08-10396K807K49.0%1,191
2026-08-071.4M2.3M60.1%2,570
2026-08-06597K1.9M31.1%577

Fails to deliver

SEC, by settlement date. JSON

As of 24 August 2026, the fails-to-deliver balance in TNDM is 499 shares, down 22,421 shares over the last settlement date. Over the last 52 readings it ranged from 2 shares (22 May 2026) to 63,014 shares (27 May 2026). The latest reading sits at the bottom of that range.

SettlementShares failedPriceValue
2026-08-24499$22.32$11K
2026-08-1322,920$23.44$537K
2026-07-31400$19.01$8K
2026-07-2269$17.60$1K
2026-07-202,128$17.08$36K
2026-07-162,011$15.28$31K
2026-07-0733,787$15.42$521K
2026-06-303$15.83$47
2026-06-2945,274$16.24$735K
2026-06-2619,337$15.76$305K
2026-06-1812$15.40$185
2026-06-16246$16.76$4K
2026-06-151,509$16.60$25K
2026-06-09772$18.47$14K
2026-06-0562$19.45$1K
2026-06-021,791$19.12$34K
2026-06-013,061$17.20$53K
2026-05-28409$14.82$6K
2026-05-2763,014$14.54$916K
2026-05-26271$14.97$4K
2026-05-222$15.76$32
2026-05-2038$13.86$527
2026-05-19252$13.53$3K
2026-05-18440$12.82$6K
2026-05-15146$14.15$2K
2026-05-04225$19.42$4K
2026-05-01142$19.53$3K
2026-04-30471$18.16$9K
2026-04-27362$20.36$7K
2026-04-24814$20.68$17K

Insider trades

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

No open-market insider trades were reported for TNDM in the last 90 days. The most recent filings are listed below; grants and option exercises carry a weaker signal than voluntary trades. Latest filing: Vosseller Leigh (EVP & CHIEF FINANCIAL OFFICER) on 2026-08-15.

DateInsiderTitleTypeSharesPriceValueOwned after
2026-08-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICERTax withholding942$22.72$21K52K
2026-08-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICEROption exercise3K$0.00$053K
2026-08-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICERTax withholding537$22.72$12K50K
2026-08-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICEROption exercise1K$0.00$051K
2026-08-15Morrison SusanEVP & Chief Admin. OfficerTax withholding495$22.72$11K53K
2026-08-15Morrison SusanEVP & Chief Admin. OfficerOption exercise2K$0.00$053K
2026-08-15Morrison SusanEVP & Chief Admin. OfficerTax withholding314$22.72$7K52K
2026-08-15Morrison SusanEVP & Chief Admin. OfficerOption exercise1K$0.00$052K
2026-08-15Kyrillos Jean-ClaudeEVP & Chief Operating OfficerTax withholding535$22.72$12K30K
2026-08-15Kyrillos Jean-ClaudeEVP & Chief Operating OfficerOption exercise1K$0.00$031K
2026-08-15Sheridan John FPRESIDENT & CEOTax withholding5K$22.72$115K160K
2026-08-15Sheridan John FPRESIDENT & CEOOption exercise10K$0.00$0165K
2026-08-15Sheridan John FPRESIDENT & CEOTax withholding3K$22.72$69K155K
2026-08-15Sheridan John FPRESIDENT & CEOOption exercise6K$0.00$0158K
2026-08-15Hansen Shannon MarieEVP & Chief Legal OfficerTax withholding976$22.72$22K32K
2026-08-15Hansen Shannon MarieEVP & Chief Legal OfficerOption exercise2K$0.00$033K
2026-08-15Hansen Shannon MarieEVP & Chief Legal OfficerTax withholding559$22.72$13K31K
2026-08-15Hansen Shannon MarieEVP & Chief Legal OfficerOption exercise1K$0.00$031K
2026-08-15Gasser Elizabeth AnneEVP, Chief Strategy OfficerTax withholding1K$22.72$23K1K
2026-08-15Gasser Elizabeth AnneEVP, Chief Strategy OfficerOption exercise2K$0.00$02K
2026-08-15Gasser Elizabeth AnneEVP, Chief Strategy OfficerTax withholding589$22.72$13K508
2026-08-15Gasser Elizabeth AnneEVP, Chief Strategy OfficerOption exercise1K$0.00$01K
2026-08-15Carpenter RickEVP & Chief Technology OfficerTax withholding820$22.72$19K32K
2026-08-15Carpenter RickEVP & Chief Technology OfficerOption exercise2K$0.00$033K
2026-08-15Carpenter RickEVP & Chief Technology OfficerTax withholding457$22.72$10K31K
2026-08-15Carpenter RickEVP & Chief Technology OfficerOption exercise897$0.00$032K
2026-06-02Gasser Elizabeth AnneEVP, Chief Strategy OfficerGift7K$0.00$00
2026-05-21TWOMEY CHRISTOPHER Jn/aOption exercise9K$0.00$024K
2026-05-21Sodhi Rajwantn/aOption exercise9K$0.00$024K
2026-05-21ROBERTSON REBECCA Bn/aOption exercise9K$0.00$023K
2026-05-21McGroddy-Goetz Kathleenn/aOption exercise9K$0.00$027K
2026-05-21Malagueira Joao Paulo Falcaon/aOption exercise9K$0.00$022K
2026-05-21Howell Peyton Rn/aOption exercise9K$0.00$030K
2026-05-21Cha Myoungiln/aOption exercise9K$0.00$022K
2026-05-21Allen Dickn/aOption exercise9K$0.00$028K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICERGrant1K$10.90$15K49K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICERTax withholding4K$12.82$48K48K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICEROption exercise10K$0.00$052K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICERTax withholding537$12.82$7K41K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICEROption exercise1K$0.00$042K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICERTax withholding540$12.82$7K40K
2026-05-15Vosseller LeighEVP & CHIEF FINANCIAL OFFICEROption exercise2K$0.00$041K
2026-05-15Sheridan John FPRESIDENT & CEOGrant1K$10.90$15K152K
2026-05-15Sheridan John FPRESIDENT & CEOTax withholding19K$12.82$243K151K
2026-05-15Sheridan John FPRESIDENT & CEOOption exercise40K$0.00$0170K
2026-05-15Sheridan John FPRESIDENT & CEOTax withholding3K$12.82$39K130K
2026-05-15Sheridan John FPRESIDENT & CEOOption exercise6K$0.00$0133K
2026-05-15Sheridan John FPRESIDENT & CEOTax withholding3K$12.82$36K127K
2026-05-15Sheridan John FPRESIDENT & CEOOption exercise5K$0.00$0130K
2026-05-15Novara Mark DavidEVP & CHIEF COMMERCIAL OFFICERTax withholding8K$12.82$101K40K

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 the rarer, stronger signal.

Planned sales (Form 144)

Newest first. JSON

6 Form 144 notices on file for TNDM worth $23K at the prices reported; 2 in the last 90 days worth $9K. Latest: MARK NOVARA filed on 2026-09-17 to sell 360 shares ($6K) from 2026-09-17.

FiledSellerSharesMarket valueOf outstandingSale fromBroker
2026-09-17MARK NOVARAOfficer360$6K0.001%2026-09-17Morgan Stanley Smith Barney LLC Executive Financial Services
2026-08-18MARK NOVARAOfficer131$3K0.000%2026-08-18Morgan Stanley Smith Barney LLC Executive Financial Services
2026-06-17MARK NOVARAOfficer361$6K0.001%2026-06-17Morgan Stanley Smith Barney LLC Executive Financial Services
2026-05-19MARK NOVARAOfficer266$4K0.000%2026-05-19Morgan Stanley Smith Barney LLC Executive Financial Services
2026-03-17MARK NOVARAOfficer187$4K0.000%2026-03-17Morgan Stanley Smith Barney LLC Executive Financial Services
2026-03-05MARK NOVARAOfficer2$470.000%2026-03-05Morgan Stanley Smith Barney LLC Executive Financial Services

Large holders (13D and 13G)

One row per reporting person, newest filing first. JSON

5 holders above 5% have filed on TNDM, all on Schedule 13G (passive). The largest reported stake is Vanguard Portfolio Management at 5.9% of the class (4,052,274 shares), filed 2026-04-29 for an event on 2026-03-31.

FiledFormHolderSharesOf classEvent
2026-08-0613G/Ano. 1Voya Financial, Inc.parent holding company149K0.2%2026-06-30
2026-05-0513GVoya Financial, Inc.parent holding company4.3M6.3%2026-03-31
2026-04-3013GVanguard Capital Managementinvestment adviser3.6M5.2%2026-03-31
2026-04-2913GVanguard Portfolio Managementinvestment adviser4.1M5.9%2026-03-31
2026-03-2713G/Ano. 8The Vanguard Groupinvestment adviser00.0%2026-03-13
2026-02-1713G/Ano. 1ArrowMark Colorado Holdings, LLCinvestment adviser2.9M4.3%2025-12-31
2025-11-1313GArrowMark Colorado Holdings, LLCinvestment adviser3.7M5.5%2025-09-30

13F holders

Tracked managers holding TNDM at their latest 13F. JSON

6 of the 30 tracked managers held TNDM at their latest 13F, $88.3M in total at quarter-end prices. Citadel Advisors is the largest at $28.0M (0.0% of its portfolio) as of 2026-06-30. Over the prior quarter 1 added shares and 4 cut.

FundQuarterSharesValueOf portfolioChange in shares
Citadel Advisors2026-06-301.9M$28.0M0.00%-423K
Millennium Management2026-06-301.3M$19.8M0.01%new or n/a
Point72 Asset Management2026-06-30911K$13.7M0.02%-6.6M
D. E. Shaw & Co.2026-06-30682K$10.3M0.00%-102K
Two Sigma Investments2026-06-30558K$8.4M0.01%-1.3M
AQR Capital Management2026-06-30534K$8.1M0.00%+202K

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.

Financials

SEC XBRL, as filed. JSON

In Q2 2026 (quarter ended 2026-06-30) TANDEM DIABETES CARE INC reported revenue of $254.6M, up 5.8% from the same quarter a year earlier, and net loss of $21.2M (-0.31 diluted EPS). In FY 2025 it generated -$9.7M of operating cash flow. As of 2026-06-30, cash was $62.8M against $602.6M of debt.

Cash
$62.8M
Debt
$602.6M
Equity
$130.4M
Total assets
$1.15B
Shares outstanding
69,578,707

Quarterly, last 8 quarters

QuarterPeriod endRevenueNet incomeMarginDiluted EPS
Q2 20262026-06-30$254.6M-$21.2M-8.3%-0.31
Q1 20262026-03-31$247.2M-$20.4M-8.2%-0.30
Q4 20252025-12-31$290.4M-$589K-0.2%-0.01
Q3 20252025-09-30$249.3M-$21.2M-8.5%-0.31
Q2 20252025-06-30$240.7M-$52.4M-21.8%-0.78
Q1 20252025-03-31$234.4M-$130.6M-55.7%-1.97
Q4 20242024-12-31$282.6M$755K0.3%0.01
Q3 20242024-09-30$244.0M-$23.3M-9.5%-0.35

Fiscal years, with buybacks and dividends

Fiscal yearEndsRevenueNet incomeOperating cash flowCapexBuybacksDividends
FY 20252025-12-31$1.01Bn/a-$9.7M$19.9M$0n/a
FY 20242024-12-31$940.2Mn/a$24.2M$19.2M$30.0Mn/a
FY 20232023-12-31$747.7Mn/a-$31.8M$26.8M$0n/a
FY 20222022-12-31$801.2Mn/a$50.5M$34.1M$0n/a
FY 20212021-12-31$702.8Mn/a$111.4M$14.2Mn/an/a

Quarters are the three-month figures the company reports; a fourth quarter marked derived is the fiscal year less the three reported quarters, since companies report it only inside the 10-K. Fiscal years are the annual figures. Buybacks are cash paid to repurchase common stock in the year (XBRL PaymentsForRepurchaseOfCommonStock), not authorizations. Balance sheet lines are as of 2026-06-30; shares outstanding as of 2026-08-03 from the cover page.

What this page is

TANDEM DIABETES CARE INC 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 pulls every series the site collects for one ticker onto one URL, keyed by the SEC's own ticker list, 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 summary sentence built from the rows (last value, change, range with dates) and its own JSON and CSV links. Nothing on the page is written by a model; the sentences change only when the data does. A page exists only for companies with data in at least two series, and every section says when its source last updated.

This page follows TANDEM DIABETES CARE INC (TNDM), SEC CIK 1438133, listed on Nasdaq, classified by the SEC as surgical & medical instruments & apparatus. The cross-market tables live on the short interest and insider transactions hubs.

Source and method

Short interest
FINRA consolidated short interestTwice a month, about eight business days after settlement. Latest 2026-08-31.JSON and CSV
Daily short volume
FINRA Reg SHO daily filesEvery trading day, loaded the following morning. Latest 2026-09-17.JSON and CSV
Fails to deliver
SEC fails-to-deliver dataTwice a month, a few weeks after the half month ends. Latest 2026-08-24.JSON and CSV
Planned sales
SEC EDGAR Form 144EDGAR read every 30 minutes; a notice is filed on or before the sell order. Latest 2026-09-17.JSON and CSV
Large holders
SEC EDGAR Schedule 13D and 13GEDGAR read every 30 minutes; 13D within five business days of crossing 5%, 13G on the passive schedule. Latest 2026-08-06.JSON and CSV
13F holders
SEC EDGAR Form 13F-HRQuarterly, filed within 45 days of quarter end; 30 tracked managers. Latest 2026-06-30.JSON and CSV
Financials
SEC XBRL company factsRefreshed weekly from the SEC's structured data; values are as filed in the 10-Q and 10-K. Latest 2026-06-30.JSON and CSV
Earnings dates
SEC EDGAR 8-K Item 2.02 (full-text search)EDGAR full-text search read twice a day; the estimate is last year's date plus 52 weeks. Latest 2026-08-06.JSON and CSV
Insider trades
SEC EDGAR Form 4EDGAR read every 30 minutes; filings are due two business days after the trade. Latest 2026-08-15.JSON and CSV
Company record
EDGAR filing index for CIK 1438133Ticker, name and exchange from the SEC's company list, refreshed weekly.
Rate limits
30 requests a minute without a key, 120 a minute with a key from a free account.

Data checks. Every dataset is checked against its source once a day. This dataset passed the last run, 18 Sep 05:40 UTC.

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 crowded short are the combination that has historically preceded squeezes; insider sells next to a crowded short 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.

Datasets

Frequently Asked Questions

How much of TNDM is sold short?
11,753,819 shares were held short at the 2026-08-31 settlement, 8.2 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 TNDM's daily short volume?
On 2026-09-17, 538,038 of the 768,305 TNDM shares reported to FINRA were sold short, 70.0% of the day's reported volume. Short volume is a flow for one day, not a position.
Does TNDM have fails to deliver?
The SEC's latest file shows 499 TNDM shares failed to deliver at settlement 2026-08-24. Fails are reported per settlement date and published twice a month with a lag.
Are TNDM insiders buying or selling?
No open-market insider trades were reported for TNDM in the last 90 days. The most recent filings are listed below; grants and option exercises carry a weaker signal than voluntary trades. Latest filing: Vosseller Leigh (EVP & CHIEF FINANCIAL OFFICER) on 2026-08-15.
Have TNDM insiders filed to sell?
6 Form 144 notices on file for TNDM worth $23K at the prices reported; 2 in the last 90 days worth $9K. Latest: MARK NOVARA filed on 2026-09-17 to sell 360 shares ($6K) from 2026-09-17.
Who owns more than 5% of TNDM?
5 holders above 5% have filed on TNDM, all on Schedule 13G (passive). The largest reported stake is Vanguard Portfolio Management at 5.9% of the class (4,052,274 shares), filed 2026-04-29 for an event on 2026-03-31.
What did TNDM report last quarter?
In Q2 2026 (quarter ended 2026-06-30) TANDEM DIABETES CARE INC reported revenue of $254.6M, up 5.8% from the same quarter a year earlier, and net loss of $21.2M (-0.31 diluted EPS). In FY 2025 it generated -$9.7M of operating cash flow. As of 2026-06-30, cash was $62.8M against $602.6M of debt.
Which funds hold TNDM?
6 of the 30 tracked managers held TNDM at their latest 13F, $88.3M in total at quarter-end prices. Citadel Advisors is the largest at $28.0M (0.0% of its portfolio) as of 2026-06-30. Over the prior quarter 1 added shares and 4 cut.

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