Inspire Medical Systems, Inc.
US ˙ NYSE ˙ US4577301090

SecurityINSP / Inspire Medical Systems, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership527,217 shares
Ownership 1.80%
Citadel Advisors Llc ownership in INSP / Inspire Medical Systems, Inc.

2026-02-17 - Citadel Advisors Llc has filed an SCHEDULE 13G/A form with the Securities and Exchange Commission (SEC) disclosing ownership of 527,217 shares of Inspire Medical Systems, Inc. (US:INSP). This represents 1.8 percent ownership of the company. In their previous filing dated 2025-10-06 , Citadel Advisors Llc had reported owning 1,713,042 shares, indicating a decrease of -69.22 percent.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (INSP) in the form of stock options. The firm currently holds call options representing 28,200 of underlying shares valued at $1,454,556 USD and put options representing 60,800 of underlying shares valued at $3,136,064 USD .

Note: prior versions of this page mistakenly stated that the share values represented the number of options, not the number of underlying shares. For more information on the data backing these reports, please see the SEC document Frequently Asked Questions About Form 13F.

Institutional Ownership: 13D/G Filings

This table shows a history of the 13D/G filings made by the investor and/or investor group. Note that the share values in this table are not directly comparable to any numbers shown in the 13F table (if any).

File
Date
Effective
Date
Form Prev
Shares
Latest
Shares
ΔShares
(Percent)
Ownership
(Percent)
ΔOwnership
(Percent)
2026-02-17 2026-02-17 13G/A 1,713,042 527,217 -69.22 1.80 -68.97
2025-10-06 2025-10-06 13G 1,713,042 5.80

Important Note: One of the primary uses of the 13D/G filings is to evaluate the ability of a firm to control a company (ie, the "beneficial ownership"). To that end, firms are required to report not just direct holdings in companies, but indirect holdings that they control. For investment firms, these indirect holdings can include shares in funds they manage, advisory accounts, and in the case of activist campaigns, pledged votes. Therefore, share counts listed in 13D/G filings can differ significantly than share counts listed in 13F filings.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

INSP / Inspire Medical Systems, Inc. Historical Put/Call Ratio
Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date
Effective
Date
Form Security Class ID Avg Price
Paid (Est)
Reported
Shares
ΔShares ΔShares
(%)
Reported
Value
(x1000)
ΔValue
(%)
Alloc
(%)
ΔAlloc ΔAlloc (%) Cost Basis
(x1000)
Unrealized
Gain/Loss
(x1000)
2026-05-15 2026-03-31 13F INSPIRE MED SYS COM 457730109 394,076 -117,242 -22.93 20,326 -56.90 0.0029
2026-02-17 2025-12-31 13F INSPIRE MED SYS COM 457730109 511,318 -1,237,091 -70.76 47,159 -63.65 0.0071
2025-11-14 2025-09-30 13F INSPIRE MED SYS COM 457730109 1,748,409 1,739,734 20,054.57 129,732 11,431.64 0.0197
2025-08-14 2025-06-30 13F INSPIRE MED SYS COM 457730109 8,675 -51,611 -85.61 1,126 -88.28 0.0002
2025-05-15 2025-03-31 13F INSPIRE MED SYS COM 457730109 60,286 7,865 15.00 9,602 -1.18 0.0018
2025-02-14 2024-12-31 13F INSPIRE MED SYS COM 457730109 52,421 -57,890 -52.48 9,718 -58.26 0.0017
2024-11-14 2024-09-30 13F INSPIRE MED SYS COM 457730109 110,311 78,660 248.52 23,281 449.73 0.0045
2024-08-14 2024-06-30 13F INSPIRE MED SYS COM 457730109 31,651 -61,340 -65.96 4,236 -78.80 0.0009
2024-05-15 2024-03-31 13F INSPIRE MED SYS COM 457730109 92,991 88,706 2,070.15 19,974 2,193.11 0.0039
2024-02-14 2023-12-31 13F INSPIRE MED SYS COM 457730109 4,285 -44,767 -91.26 872 -91.05 0.0002
2023-11-14 2023-09-30 13F INSPIRE MED SYS COM 457730109 49,052 -270,620 -84.66 9,734 -90.62 0.0021
2023-08-14 2023-06-30 13F INSPIRE MED SYS COM 457730109 319,672 14,460 4.74 103,778 45.27 0.0215
2023-05-15 2023-03-31 13F INSPIRE MED SYS COM 457730109 305,212 -327,118 -51.73 71,441 -55.15 0.0157
2023-02-14 2022-12-31 13F INSPIRE MED SYS COM 457730109 632,330 82,864 15.08 159,271 63.42 0.0372
2022-11-14 2022-09-30 13F INSPIRE MED SYS COM 457730109 549,466 238,946 76.95 97,459 71.82 0.0222
2022-08-15 2022-06-30 13F INSPIRE MED SYS COM 457730109 310,520 237,060 322.71 56,722 200.80 0.0146
2022-05-16 2022-03-31 13F INSPIRE MED SYS COM 457730109 73,460 -197,226 -72.86 18,857 -69.72 0.0039
2022-02-14 2021-12-31 13F INSPIRE MED SYS COM 457730109 270,686 179,825 197.91 62,274 194.30 0.0127
2021-11-15 2021-09-30 13F INSPIRE MED SYS Cmn 457730109 90,861 -198,533 -68.60 21,160 -62.17 0.0044
2021-08-16 2021-06-30 13F INSPIRE MED SYS COM 457730109 289,394 236,335 445.42 55,929 409.23 0.0125
2021-05-21 2021-03-31 13F/A-1 INSPIRE MED SYS COM 457730109 53,059 17,393 48.77 10,983 63.71 0.0027
2021-05-17 2021-03-31 13F INSPIRE MED SYS COM 457730109 53,059 17,393 10,983 0.0027
2021-02-16 2020-12-31 13F INSPIRE MED SYS COM 457730109 35,666 11,588 48.13 6,709 115.93 0.0017
2020-11-16 2020-09-30 13F INSPIRE MED SYS COM 457730109 24,078 21,198 736.04 3,107 1,137.85 0.0009
2020-08-14 2020-06-30 13F INSPIRE MED SYS Cmn 457730109 2,880 -61,474 -95.52 251 -93.53 0.0001
2020-05-15 2020-03-31 13F INSPIRE MED SYS Cmn 457730109 64,354 38,029 144.46 3,879 98.52 0.0017
2020-02-14 2019-12-31 13F INSPIRE MED SYS Cmn 457730109 26,325 -44,090 -62.61 1,954 -54.53 0.0008
2019-11-14 2019-09-30 13F INSPIRE MED SYS Cmn 457730109 70,415 -212,873 -75.14 4,297 -74.99 0.0020
2019-08-14 2019-06-30 13F INSPIRE MED SYS Cmn 457730109 283,288 -90,692 -24.25 17,181 -19.09 0.0079
2019-05-15 2019-03-31 13F INSPIRE MED SYS Cmn 457730109 373,980 256,600 218.61 21,234 328.19 0.0106
2019-02-14 2018-12-31 13F INSPIRE MED SYS Cmn 457730109 117,380 -73,256 -38.43 4,959 -38.18 0.0027
2018-11-13 2018-09-30 13F INSPIRE MED SYS Cmn 457730109 190,636 157,844 481.35 8,022 586.23 0.0036
2018-08-14 2018-06-30 13F/A-1 INSPIRE MED SYS Cmn 457730109 32,792 32,792 1,169 0.0006
2018-08-10 2018-06-30 13F INSPIRE MED SYS Cmn 457730109 32,792 1,169 0.0006
Disclosed Call Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share
Price
Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F INSPIRE MED SYS COM Call 28,200 78.48 1,455 -0.21 n/a n/a n/a
2026-02-17 2025-12-31 13F INSPIRE MED SYS COM Call 15,800 -48.37 1,457 -35.81 n/a n/a n/a
2025-11-14 2025-09-30 13F INSPIRE MED SYS COM Call 30,600 38.46 2,271 -20.82 n/a n/a n/a
2025-08-14 2025-06-30 13F INSPIRE MED SYS COM Call 22,100 -50.45 2,868 -59.64 n/a n/a n/a
2025-05-15 2025-03-31 13F INSPIRE MED SYS COM Call 44,600 -8.04 7,104 -20.99 n/a n/a n/a
2025-02-14 2024-12-31 13F INSPIRE MED SYS COM Call 48,500 -44.25 8,991 -51.04 n/a n/a n/a
2024-11-14 2024-09-30 13F INSPIRE MED SYS COM Call 87,000 -22.67 18,361 21.96 n/a n/a n/a
2024-08-14 2024-06-30 13F INSPIRE MED SYS COM Call 112,500 7.24 15,056 -33.18 n/a n/a n/a
2024-05-15 2024-03-31 13F INSPIRE MED SYS COM Call 104,900 44.69 22,531 52.77 n/a n/a n/a
2024-02-14 2023-12-31 13F INSPIRE MED SYS COM Call 72,500 -29.41 14,749 -27.63 n/a n/a n/a
2023-11-14 2023-09-30 13F INSPIRE MED SYS COM Call 102,700 79.86 20,380 9.94 n/a n/a n/a
2023-08-14 2023-06-30 13F INSPIRE MED SYS COM Call 57,100 37.26 18,537 90.37 n/a n/a n/a
2023-05-15 2023-03-31 13F INSPIRE MED SYS COM Call 41,600 -59.45 9,737 -62.32 n/a n/a n/a
2023-02-14 2022-12-31 13F INSPIRE MED SYS COM Call 102,600 68.20 25,843 138.84 n/a n/a n/a
2022-11-14 2022-09-30 13F INSPIRE MED SYS COM Call 61,000 23.98 10,820 20.40 n/a n/a n/a
2022-08-15 2022-06-30 13F INSPIRE MED SYS COM Call 49,200 3.58 8,987 -26.29 n/a n/a n/a
2022-05-16 2022-03-31 13F INSPIRE MED SYS COM Call 47,500 40.53 12,193 56.80 n/a n/a n/a
2022-02-14 2021-12-31 13F INSPIRE MED SYS COM Call 33,800 76.04 7,776 73.92 n/a n/a n/a
2021-11-15 2021-09-30 13F INSPIRE MED SYS Cmn Call 19,200 66.96 4,471 101.22 n/a n/a n/a
2021-08-16 2021-06-30 13F INSPIRE MED SYS COM Call 11,500 -4.96 2,222 -11.30 n/a n/a n/a
2021-05-21 2021-03-31 13F/A INSPIRE MED SYS COM Call 12,100 -42.92 2,505 -37.19 n/a n/a n/a
2021-05-17 2021-03-31 13F INSPIRE MED SYS COM Call 12,100 2,505 n/a n/a n/a
2021-02-16 2020-12-31 13F INSPIRE MED SYS COM Call 21,200 -40.45 3,988 -13.19 n/a n/a n/a
2020-11-16 2020-09-30 13F INSPIRE MED SYS COM Call 35,600 119.75 4,594 225.82 n/a n/a n/a
2020-08-14 2020-06-30 13F INSPIRE MED SYS Cmn Call 16,200 125.00 1,410 224.88 n/a n/a n/a
2020-05-15 2020-03-31 13F INSPIRE MED SYS Cmn Call 7,200 -4.00 434 -22.08 n/a n/a n/a
2020-02-14 2019-12-31 13F INSPIRE MED SYS Cmn Call 7,500 -59.46 557 -50.66 n/a n/a n/a
2019-11-14 2019-09-30 13F INSPIRE MED SYS Cmn Call 18,500 68.18 1,129 69.27 n/a n/a n/a
2019-08-14 2019-06-30 13F INSPIRE MED SYS Cmn Call 11,000 667 n/a n/a n/a
2019-05-15 2019-03-31 13F INSPIRE MED SYS Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2019-02-14 2018-12-31 13F INSPIRE MED SYS Cmn Call 5,800 245 n/a n/a n/a
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2026-05-15 2026-03-31 13F INSPIRE MED SYS COM Put 60,800 72.24 3,136 -3.66 n/a n/a n/a
2026-02-17 2025-12-31 13F INSPIRE MED SYS COM Put 35,300 -55.09 3,256 -44.19 n/a n/a n/a
2025-11-14 2025-09-30 13F INSPIRE MED SYS COM Put 78,600 194.38 5,832 68.36 n/a n/a n/a
2025-08-14 2025-06-30 13F INSPIRE MED SYS COM Put 26,700 -71.38 3,465 -76.69 n/a n/a n/a
2025-05-15 2025-03-31 13F INSPIRE MED SYS COM Put 93,300 42.44 14,861 22.39 n/a n/a n/a
2025-02-14 2024-12-31 13F INSPIRE MED SYS COM Put 65,500 9.35 12,142 -3.95 n/a n/a n/a
2024-11-14 2024-09-30 13F INSPIRE MED SYS COM Put 59,900 -34.39 12,642 3.46 n/a n/a n/a
2024-08-14 2024-06-30 13F INSPIRE MED SYS COM Put 91,300 -23.34 12,219 -52.24 n/a n/a n/a
2024-05-15 2024-03-31 13F INSPIRE MED SYS COM Put 119,100 44.19 25,581 52.24 n/a n/a n/a
2024-02-14 2023-12-31 13F INSPIRE MED SYS COM Put 82,600 40.72 16,803 44.26 n/a n/a n/a
2023-11-14 2023-09-30 13F INSPIRE MED SYS COM Put 58,700 12.88 11,648 -31.00 n/a n/a n/a
2023-08-14 2023-06-30 13F INSPIRE MED SYS COM Put 52,000 8.11 16,881 49.95 n/a n/a n/a
2023-05-15 2023-03-31 13F INSPIRE MED SYS COM Put 48,100 2.78 11,259 -4.49 n/a n/a n/a
2023-02-14 2022-12-31 13F INSPIRE MED SYS COM Put 46,800 44.00 11,788 104.46 n/a n/a n/a
2022-11-14 2022-09-30 13F INSPIRE MED SYS COM Put 32,500 -24.07 5,765 -26.26 n/a n/a n/a
2022-08-15 2022-06-30 13F INSPIRE MED SYS COM Put 42,800 99.07 7,818 41.66 n/a n/a n/a
2022-05-16 2022-03-31 13F INSPIRE MED SYS COM Put 21,500 38.71 5,519 54.77 n/a n/a n/a
2022-02-14 2021-12-31 13F INSPIRE MED SYS COM Put 15,500 34.78 3,566 33.16 n/a n/a n/a
2021-11-15 2021-09-30 13F INSPIRE MED SYS Cmn Put 11,500 -44.17 2,678 -32.73 n/a n/a n/a
2021-08-16 2021-06-30 13F INSPIRE MED SYS COM Put 20,600 -70.78 3,981 -72.72 n/a n/a n/a
2021-05-21 2021-03-31 13F/A INSPIRE MED SYS COM Put 70,500 2.77 14,593 13.10 n/a n/a n/a
2021-05-17 2021-03-31 13F INSPIRE MED SYS COM Put 70,500 14,593 n/a n/a n/a
2021-02-16 2020-12-31 13F INSPIRE MED SYS COM Put 68,600 134.93 12,903 242.44 n/a n/a n/a
2020-11-16 2020-09-30 13F INSPIRE MED SYS COM Put 29,200 35.81 3,768 101.39 n/a n/a n/a
2020-08-14 2020-06-30 13F INSPIRE MED SYS Cmn Put 21,500 290.91 1,871 463.55 n/a n/a n/a
2020-05-15 2020-03-31 13F INSPIRE MED SYS Cmn Put 5,500 -47.62 332 -57.38 n/a n/a n/a
2020-02-14 2019-12-31 13F INSPIRE MED SYS Cmn Put 10,500 -43.55 779 -31.37 n/a n/a n/a
2019-11-14 2019-09-30 13F INSPIRE MED SYS Cmn Put 18,600 304.35 1,135 306.81 n/a n/a n/a
2019-08-14 2019-06-30 13F INSPIRE MED SYS Cmn Put 4,600 -51.58 279 -48.24 n/a n/a n/a
2019-05-15 2019-03-31 13F INSPIRE MED SYS Cmn Put 9,500 539 n/a n/a n/a
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.