Bel Fuse Inc.

SecurityBELFB / Bel Fuse Inc.
InstitutionAdvisory Research Inc
Latest Disclosed Ownership119,364 shares
Latest Disclosed Value $ 23,631,685
Advisory Research Inc reports 11.44% decrease in ownership of BELFB / Bel Fuse Inc.

On May 14, 2026 - Advisory Research Inc filed a 13F-HR form disclosing ownership of 119,364 shares of Bel Fuse Inc. (US:BELFB) valued at $23,631,685 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 134,790 shares of Bel Fuse Inc.. This represents a change in shares of -11.44% during the quarter. The current value of the position is $33,008,921 USD.

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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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)
2026-05-14 2026-03-31 13F BEL FUSE CL B 077347300 119,364 -15,426 -11.44 23,632 3.35 2.4670
2026-02-13 2025-12-31 13F BEL FUSE CL B 077347300 134,790 -58,770 -30.36 22,864 -16.23 2.8734
2025-11-13 2025-09-30 13F BEL FUSE CL B 077347300 193,560 -197,298 -50.48 27,296 -28.51 3.5847
2025-08-13 2025-06-30 13F BEL FUSE CL B 077347300 390,858 15,769 4.20 38,183 35.98 5.8659
2025-05-14 2025-03-31 13F BEL FUSE CL B 077347300 375,089 61,643 19.67 28,079 8.63 4.9496
2025-02-13 2024-12-31 13F BEL FUSE CL B 077347300 313,446 67,460 27.42 25,850 33.85 4.2964
2024-11-14 2024-09-30 13F BEL FUSE CL B 077347300 245,986 6,596 2.76 19,312 23.66 3.4310
2024-08-13 2024-06-30 13F BEL FUSE CL B 077347300 239,390 300 0.13 15,618 8.31 2.9378
2024-05-14 2024-03-31 13F BEL FUSE CL B 077347300 239,090 48,904 25.71 14,420 13.55 2.8671
2024-02-13 2023-12-31 13F Bel Fuse Inc. Class B COM 077347300 190,186 165,800 679.90 12,699 991.83 1.9587
2023-11-13 2023-09-30 13F Bel Fuse Inc. Class B COM 077347300 24,386 17,925 277.43 1,164 214.32 0.1616
2023-08-14 2023-06-30 13F Bel Fuse Inc. Class B COM 077347300 6,461 6,461 371 0.0476
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.