Fuel Tech, Inc.
US ˙ NasdaqCM ˙ US3595231073

SecurityFTEK / Fuel Tech, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership221,399 shares
Latest Disclosed Value $ 270,107
Citadel Advisors Llc ownership in FTEK / Fuel Tech, Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 221,399 shares of Fuel Tech, Inc. (US:FTEK) valued at $270,107 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 504,017 shares of Fuel Tech, Inc.. This represents a change in shares of -56.07% during the quarter. The current value of the position is $301,103 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (FTEK) in the form of stock options. The firm currently holds call options representing 0 of underlying shares valued at $0 USD and put options representing 0 of underlying shares valued at $0 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: 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.

FTEK / Fuel Tech, 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 FUEL TECH COM 359523107 221,399 -282,618 -56.07 270 -65.65 0.0000
2026-02-17 2025-12-31 13F FUEL TECH COM 359523107 504,017 376,994 296.79 786 106.30 0.0001
2025-11-14 2025-09-30 13F FUEL TECH COM 359523107 127,023 96,907 321.78 381 408.00 0.0001
2025-08-14 2025-06-30 13F FUEL TECH COM 359523107 30,116 -144,165 -82.72 76 -58.79 0.0000
2025-05-15 2025-03-31 13F FUEL TECH COM 359523107 174,281 -73,275 -29.60 183 -29.73 0.0000
2025-02-14 2024-12-31 13F FUEL TECH COM 359523107 247,556 119,639 93.53 260 93.28 0.0000
2024-11-14 2024-09-30 13F FUEL TECH COM 359523107 127,917 39,391 44.50 134 42.55 0.0000
2024-08-14 2024-06-30 13F FUEL TECH COM 359523107 88,526 40,507 84.36 95 62.07 0.0000
2024-05-15 2024-03-31 13F FUEL TECH COM 359523107 48,019 2,473 5.43 58 23.40 0.0000
2024-02-14 2023-12-31 13F FUEL TECH COM 359523107 45,546 32,175 240.63 48 213.33 0.0000
2023-11-14 2023-09-30 13F FUEL TECH COM 359523107 13,371 -27,180 -67.03 16 -71.70 0.0000
2023-08-14 2023-06-30 13F FUEL TECH COM 359523107 40,551 -55,615 -57.83 54 -56.91 0.0000
2023-05-15 2023-03-31 13F FUEL TECH COM 359523107 96,166 56,420 141.95 123 146.00 0.0000
2023-02-14 2022-12-31 13F FUEL TECH COM 359523107 39,746 39,746 50 0.0000
2022-05-16 2022-03-31 13F FUEL TECH COM 359523107 0 -118,903 -100.00 0 -100.00
2022-02-14 2021-12-31 13F FUEL TECH COM 359523107 118,903 118,903 166 0.0000
2021-08-16 2021-06-30 13F FUEL TECH COM 359523107 0 -46,910 -100.00 0 -100.00
2021-05-21 2021-03-31 13F/A-1 FUEL TECH COM 359523107 46,910 12,292 35.51 147 9.70 0.0000
2021-05-17 2021-03-31 13F FUEL TECH COM 359523107 46,910 12,292 147 0.0000
2021-02-16 2020-12-31 13F FUEL TECH COM 359523107 34,618 34,618 134 0.0000
2019-08-14 2019-06-30 13F FUEL TECH Cmn 359523107 0 -41,631 -100.00 0 -100.00
2019-05-15 2019-03-31 13F FUEL TECH Cmn 359523107 41,631 23,610 131.01 70 233.33 0.0000
2019-02-14 2018-12-31 13F FUEL TECH Cmn 359523107 18,021 18,021 21 0.0000
2018-11-13 2018-09-30 13F FUEL TECH Cmn 359523107 0 -11,957 -100.00 0 -100.00
2018-08-14 2018-06-30 13F/A-1 FUEL TECH Cmn 359523107 11,957 699 6.21 13 -7.14 0.0000
2018-08-10 2018-06-30 13F FUEL TECH Cmn 359523107 11,957 699 13
2018-05-14 2018-03-31 13F/A-1 FUEL TECH Cmn 359523107 11,258 -15,768 -58.34 14 -53.33 0.0000
2018-05-11 2018-03-31 13F FUEL TECH Cmn 359523107 11,258 -15,768 14
2018-02-09 2017-12-31 13F FUEL TECH Cmn 359523107 27,026 2,820 11.65 30 20.00 0.0000
2017-11-09 2017-09-30 13F FUEL TECH Cmn 359523107 24,206 7,448 44.44 25 78.57 0.0000
2017-08-11 2017-06-30 13F FUEL TECH Cmn 359523107 16,758 16,758 14 0.0000
2017-05-12 2017-03-31 13F FUEL TECH Cmn 359523107 0 -14,258 -100.00 0 -100.00
2017-02-10 2016-12-31 13F FUEL TECH Cmn 359523107 14,258 14,258 16 0.0000
2015-08-14 2015-06-30 13F FUEL TECH INC CMN STOCK Cmn 359523107 0 -26,133 -100.00 0 -100.00
2015-05-15 2015-03-31 13F FUEL TECH INC CMN STOCK Cmn 359523107 26,133 -17,627 -40.28 82 -50.90 0.0001
2015-02-17 2014-12-31 13F FUEL TECH INC CMN STOCK Cmn 359523107 43,760 299 0.69 167 -9.73 0.0002
2014-11-14 2014-09-30 13F FUEL TECH INC CMN STOCK Cmn 359523107 43,461 -4,451 -9.29 185 -31.48 0.0002
2014-08-14 2014-06-30 13F FUEL TECH INC CMN STOCK Cmn 359523107 47,912 -86,103 -64.25 270 -59.70 0.0004
2014-05-15 2014-03-31 13F FUEL TECH INC CMN STOCK Cmn 359523107 134,015 128,988 2,565.90 670 1,761.11 0.0009
2014-02-14 2013-12-31 13F FUEL TECH INC CMN STOCK Cmn 359523107 5,027 -30,191 -85.73 36 -76.62 0.0000
2013-11-14 2013-09-30 13F FUEL TECH INC CMN STOCK Cmn 359523107 35,218 -7,493 -17.54 154 -6.10 0.0002
2013-08-14 2013-06-30 13F FUEL TECH INC CMN STOCK Cmn 359523107 42,711 42,711 164 0.0003
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 FUEL TECH COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2026-02-17 2025-12-31 13F FUEL TECH COM Call 31,800 -74.54 50 -86.90 n/a n/a n/a
2025-11-14 2025-09-30 13F FUEL TECH COM Call 124,900 907.26 375 1,106.45 n/a n/a n/a
2025-08-14 2025-06-30 13F FUEL TECH COM Call 12,400 4,033.33 31 n/a n/a n/a
2025-05-15 2025-03-31 13F FUEL TECH COM Call 300 -98.77 0 -100.00 n/a n/a n/a
2025-02-14 2024-12-31 13F FUEL TECH COM Call 24,400 -14.08 26 -13.79 n/a n/a n/a
2024-11-14 2024-09-30 13F FUEL TECH COM Call 28,400 14,100.00 30 n/a n/a n/a
2024-08-14 2024-06-30 13F FUEL TECH COM Call 200 -77.78 0 -100.00 n/a n/a n/a
2024-05-15 2024-03-31 13F FUEL TECH COM Call 900 -10.00 1 0.00 n/a n/a n/a
2024-02-14 2023-12-31 13F FUEL TECH COM Call 1,000 -94.68 1 -95.45 n/a n/a n/a
2023-11-14 2023-09-30 13F FUEL TECH COM Call 18,800 -45.66 22 -51.11 n/a n/a n/a
2023-08-14 2023-06-30 13F FUEL TECH COM Call 34,600 401.45 46 462.50 n/a n/a n/a
2023-05-15 2023-03-31 13F FUEL TECH COM Call 6,900 23.21 9 14.29 n/a n/a n/a
2023-02-14 2022-12-31 13F FUEL TECH COM Call 5,600 7 n/a n/a n/a
2022-08-15 2022-06-30 13F FUEL TECH COM Call 0 -100.00 0 -100.00 n/a n/a n/a
2022-05-16 2022-03-31 13F FUEL TECH COM Call 19,500 28 n/a n/a n/a
2022-02-14 2021-12-31 13F FUEL TECH Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2021-11-15 2021-09-30 13F FUEL TECH Cmn Call 26,400 -30.71 46 -48.89 n/a n/a n/a
2021-08-16 2021-06-30 13F FUEL TECH COM Call 38,100 -55.75 90 -66.67 n/a n/a n/a
2021-05-21 2021-03-31 13F/A FUEL TECH COM Call 86,100 84.37 270 49.17 n/a n/a n/a
2021-05-17 2021-03-31 13F FUEL TECH COM Call 86,100 270 n/a n/a n/a
2021-02-16 2020-12-31 13F FUEL TECH COM Call 46,700 181 n/a n/a n/a
2015-08-14 2015-06-30 13F FUEL TECH INC CMN STOCK Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2015-05-15 2015-03-31 13F FUEL TECH INC CMN STOCK Cmn Call 1,000 3 n/a n/a n/a
2015-02-17 2014-12-31 13F FUEL TECH INC CMN STOCK Cmn Call 0 -100.00 0 -100.00 n/a n/a n/a
2014-11-14 2014-09-30 13F FUEL TECH INC CMN STOCK Cmn Call 1,900 -78.65 8 -84.00 n/a n/a n/a
2014-08-14 2014-06-30 13F FUEL TECH INC CMN STOCK Cmn Call 8,900 -22.61 50 -13.79 n/a n/a n/a
2014-05-15 2014-03-31 13F FUEL TECH INC CMN STOCK Cmn Call 11,500 57.53 58 11.54 n/a n/a n/a
2014-02-14 2013-12-31 13F FUEL TECH INC CMN STOCK Cmn Call 7,300 421.43 52 766.67 n/a n/a n/a
2013-11-14 2013-09-30 13F FUEL TECH INC CMN STOCK Cmn Call 1,400 180.00 6 200.00 n/a n/a n/a
2013-08-14 2013-06-30 13F FUEL TECH INC CMN STOCK Cmn Call 500 2 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
(%)
2025-11-14 2025-09-30 13F FUEL TECH COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2025-08-14 2025-06-30 13F FUEL TECH COM Put 123,200 12,220.00 310 30,900.00 n/a n/a n/a
2025-05-15 2025-03-31 13F FUEL TECH COM Put 1,000 42.86 1 n/a n/a n/a
2025-02-14 2024-12-31 13F FUEL TECH COM Put 700 -93.00 1 -100.00 n/a n/a n/a
2024-11-14 2024-09-30 13F FUEL TECH COM Put 10,000 1,900.00 10 n/a n/a n/a
2024-08-14 2024-06-30 13F FUEL TECH COM Put 500 -92.31 1 -100.00 n/a n/a n/a
2024-05-15 2024-03-31 13F FUEL TECH COM Put 6,500 400.00 8 600.00 n/a n/a n/a
2024-02-14 2023-12-31 13F FUEL TECH COM Put 1,300 333.33 1 n/a n/a n/a
2023-11-14 2023-09-30 13F FUEL TECH COM Put 300 0.00 0 n/a n/a n/a
2023-08-14 2023-06-30 13F FUEL TECH COM Put 300 -66.67 0 -100.00 n/a n/a n/a
2023-05-15 2023-03-31 13F FUEL TECH COM Put 900 12.50 1 0.00 n/a n/a n/a
2023-02-14 2022-12-31 13F FUEL TECH COM Put 800 1 n/a n/a n/a
2022-11-14 2022-09-30 13F FUEL TECH COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2022-08-15 2022-06-30 13F FUEL TECH COM Put 27,900 35 n/a n/a n/a
2022-03-11 2021-09-30 13F/A FUEL TECH COM Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-11-15 2021-09-30 13F FUEL TECH COM Put 0 0 n/a n/a n/a
2021-08-16 2021-06-30 13F FUEL TECH COM Put 18,500 17.09 43 -14.00 n/a n/a n/a
2021-05-21 2021-03-31 13F/A FUEL TECH COM Put 15,800 -18.13 50 -33.33 n/a n/a n/a
2021-05-17 2021-03-31 13F FUEL TECH COM Put 15,800 50 n/a n/a n/a
2021-02-16 2020-12-31 13F FUEL TECH COM Put 19,300 75 n/a n/a n/a
2015-08-14 2015-06-30 13F FUEL TECH INC CMN STOCK Cmn Put 0 -100.00 0 -100.00 n/a n/a n/a
2015-05-15 2015-03-31 13F FUEL TECH INC CMN STOCK Cmn Put 200 1 n/a n/a n/a
2015-02-17 2014-12-31 13F FUEL TECH INC CMN STOCK Cmn Put 0 -100.00 0 -100.00 n/a n/a n/a
2014-11-14 2014-09-30 13F FUEL TECH INC CMN STOCK Cmn Put 5,400 -11.48 23 -32.35 n/a n/a n/a
2014-08-14 2014-06-30 13F FUEL TECH INC CMN STOCK Cmn Put 6,100 -18.67 34 -10.53 n/a n/a n/a
2014-05-15 2014-03-31 13F FUEL TECH INC CMN STOCK Cmn Put 7,500 -30.56 38 -50.65 n/a n/a n/a
2014-02-14 2013-12-31 13F FUEL TECH INC CMN STOCK Cmn Put 10,800 671.43 77 1,183.33 n/a n/a n/a
2013-11-14 2013-09-30 13F FUEL TECH INC CMN STOCK Cmn Put 1,400 6 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.