Bel Fuse Inc.

SecurityBELFB / Bel Fuse Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership32,527 shares
Latest Disclosed Value $ 6,439,695
Citadel Advisors Llc ownership in BELFB / Bel Fuse Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 32,527 shares of Bel Fuse Inc. (US:BELFB) valued at $6,439,695 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 3,947 shares of Bel Fuse Inc.. This represents a change in shares of 724.09% during the quarter. The current value of the position is $8,540,289 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (BELFB) in the form of stock options. The firm currently holds call options representing 29,000 of underlying shares valued at $5,741,420 USD and put options representing 1,800 of underlying shares valued at $356,364 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.

BELFB / Bel Fuse 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 BEL FUSE CL B 077347300 32,527 28,580 724.09 6,440 862.48 0.0009
2026-02-17 2025-12-31 13F BEL FUSE CL B 077347300 3,947 -92,103 -95.89 670 -95.06 0.0001
2025-11-14 2025-09-30 13F BEL FUSE CL B 077347300 96,050 72,585 309.33 13,545 490.92 0.0021
2025-08-14 2025-06-30 13F BEL FUSE CL B 077347300 23,465 23,465 2,292 0.0004
2025-05-15 2025-03-31 13F BEL FUSE CL B 077347300 0 -7,699 -100.00 0 -100.00
2025-02-14 2024-12-31 13F BEL FUSE CL B 077347300 7,699 -33,481 -81.30 635 -74.47 0.0001
2024-05-15 2024-03-31 13F BEL FUSE CL B 077347300 41,180 5,022 13.89 2,484 2.86 0.0005
2024-02-14 2023-12-31 13F BEL FUSE CL B 077347300 36,158 8,844 32.38 2,414 85.26 0.0005
2023-11-14 2023-09-30 13F BEL FUSE CL B 077347300 27,314 19,372 243.92 1,303 186.37 0.0003
2023-08-14 2023-06-30 13F BEL FUSE CL B 077347300 7,942 -2,963 -27.17 456 11.25 0.0001
2023-05-15 2023-03-31 13F BEL FUSE CL B 077347300 10,905 -97,163 -89.91 410 -88.50 0.0001
2023-02-14 2022-12-31 13F BEL FUSE CL B 077347300 108,068 45,245 72.02 3,558 124.27 0.0008
2022-11-14 2022-09-30 13F BEL FUSE CL B 077347300 62,823 8,348 15.32 1,586 87.03 0.0004
2022-08-15 2022-06-30 13F BEL FUSE CL B 077347300 54,475 15,883 41.16 848 23.26 0.0002
2022-05-16 2022-03-31 13F BEL FUSE CL B 077347300 38,592 -22,796 -37.13 688 -13.24 0.0001
2022-02-14 2021-12-31 13F BEL FUSE CL B 077347300 61,388 3,678 6.37 793 10.60 0.0002
2021-11-15 2021-09-30 13F BEL FUSE Cmn 077347300 57,710 57,710 717 0.0001
2015-05-15 2015-03-31 13F BEL FUSE INC CMN STOCK - CLASS B Cmn 077347300 0 -10,729 -100.00 0 -100.00
2015-02-17 2014-12-31 13F BEL FUSE INC CMN STOCK - CLASS B Cmn 077347300 10,729 -2,194 -16.98 293 -8.44 0.0004
2014-11-14 2014-09-30 13F BEL FUSE INC CMN STOCK - CLASS B Cmn 077347300 12,923 886 7.36 320 3.56 0.0004
2014-08-14 2014-06-30 13F BEL FUSE INC CMN STOCK - CLASS B Cmn 077347300 12,037 -9,095 -43.04 309 -33.26 0.0004
2014-05-15 2014-03-31 13F BEL FUSE INC CMN STOCK - CLASS B Cmn 077347300 21,132 5,793 37.77 463 41.59 0.0006
2014-02-14 2013-12-31 13F BEL FUSE INC CMN STOCK - CLASS B Cmn 077347300 15,339 15,339 327 0.0004
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 BEL FUSE CL B Call 29,000 100.00 5,741 133.47 n/a n/a n/a
2026-02-17 2025-12-31 13F BEL FUSE CL B Call 14,500 95.95 2,460 135.76 n/a n/a n/a
2025-11-14 2025-09-30 13F BEL FUSE CL B Call 7,400 -33.93 1,044 -4.66 n/a n/a n/a
2025-08-14 2025-06-30 13F BEL FUSE CL B Call 11,200 119.61 1,094 187.14 n/a n/a n/a
2025-05-15 2025-03-31 13F BEL FUSE CL B Call 5,100 183.33 382 157.43 n/a n/a n/a
2025-02-14 2024-12-31 13F BEL FUSE CL B Call 1,800 -79.78 148 -78.80 n/a n/a n/a
2024-11-14 2024-09-30 13F BEL FUSE CL B Call 8,900 -28.23 699 -13.61 n/a n/a n/a
2024-08-14 2024-06-30 13F BEL FUSE CL B Call 12,400 -43.89 809 -39.34 n/a n/a n/a
2024-05-15 2024-03-31 13F BEL FUSE CL B Call 22,100 -22.73 1,333 -30.23 n/a n/a n/a
2024-02-14 2023-12-31 13F BEL FUSE CL B Call 28,600 -26.67 1,910 2.58 n/a n/a n/a
2023-11-14 2023-09-30 13F BEL FUSE CL B Call 39,000 197.71 1,861 147.47 n/a n/a n/a
2023-08-14 2023-06-30 13F BEL FUSE CL B Call 13,100 191.11 752 344.97 n/a n/a n/a
2023-05-15 2023-03-31 13F BEL FUSE CL B Call 4,500 28.57 169 46.96 n/a n/a n/a
2023-02-14 2022-12-31 13F BEL FUSE CL B Call 3,500 115 n/a n/a n/a
2022-11-14 2022-09-30 13F BEL FUSE CL B Call 0 -100.00 0 -100.00 n/a n/a n/a
2022-08-15 2022-06-30 13F BEL FUSE CL B Call 11,400 -5.00 177 -17.29 n/a n/a n/a
2022-05-16 2022-03-31 13F BEL FUSE CL B Call 12,000 214 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 BEL FUSE CL B Put 1,800 356 n/a n/a n/a
2025-08-14 2025-06-30 13F BEL FUSE CL B Put 0 -100.00 0 -100.00 n/a n/a n/a
2025-05-15 2025-03-31 13F BEL FUSE CL B Put 600 100.00 45 83.33 n/a n/a n/a
2025-02-14 2024-12-31 13F BEL FUSE CL B Put 300 -93.18 25 -93.04 n/a n/a n/a
2024-11-14 2024-09-30 13F BEL FUSE CL B Put 4,400 -45.68 345 -34.66 n/a n/a n/a
2024-08-14 2024-06-30 13F BEL FUSE CL B Put 8,100 -37.21 528 -32.05 n/a n/a n/a
2024-05-15 2024-03-31 13F BEL FUSE CL B Put 12,900 -6.52 778 -15.64 n/a n/a n/a
2024-02-14 2023-12-31 13F BEL FUSE CL B Put 13,800 -22.03 921 9.12 n/a n/a n/a
2023-11-14 2023-09-30 13F BEL FUSE CL B Put 17,700 129.87 845 90.95 n/a n/a n/a
2023-08-14 2023-06-30 13F BEL FUSE CL B Put 7,700 67.39 442 156.98 n/a n/a n/a
2023-05-15 2023-03-31 13F BEL FUSE CL B Put 4,600 109.09 173 138.89 n/a n/a n/a
2023-02-14 2022-12-31 13F BEL FUSE CL B Put 2,200 72 n/a n/a n/a
2022-02-14 2021-12-31 13F BEL FUSE Cmn Put 0 -100.00 0 -100.00 n/a n/a n/a
2021-11-15 2021-09-30 13F BEL FUSE Cmn Put 13,500 13.45 168 -1.75 n/a n/a n/a
2021-08-16 2021-06-30 13F BEL FUSE CL B Put 11,900 171 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.