Allegro MicroSystems, Inc.
US ˙ NasdaqGS ˙ US01749D1054

SecurityALGM / Allegro MicroSystems, Inc.
InstitutionCitadel Advisors Llc
ManagerKen Griffin
Latest Disclosed Ownership399,444 shares
Latest Disclosed Value $ 12,594,469
Citadel Advisors Llc ownership in ALGM / Allegro MicroSystems, Inc.

On May 15, 2026 - Citadel Advisors Llc filed a 13F-HR form disclosing ownership of 399,444 shares of Allegro MicroSystems, Inc. (US:ALGM) valued at $12,594,469 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 17, 2026 disclosing 2,560,520 shares of Allegro MicroSystems, Inc.. This represents a change in shares of -84.40% during the quarter. The current value of the position is $21,214,471 USD.

Citadel Advisors Llc has a history of taking positions in derivatives of the underlying security (ALGM) in the form of stock options. The firm currently holds call options representing 21,900 of underlying shares valued at $690,507 USD and put options representing 45,600 of underlying shares valued at $1,437,768 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.

ALGM / Allegro MicroSystems, 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 ALLEGRO MICROSYSTEMS COM 01749D105 399,444 -2,161,076 -84.40 12,594 -81.35 0.0018
2026-02-17 2025-12-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 2,560,520 2,228,889 672.10 67,547 597.57 0.0090
2025-11-14 2025-09-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 331,631 -1,187,777 -78.17 9,684 -81.36 0.0015
2025-08-14 2025-06-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 1,519,408 -2,814,205 -64.94 51,949 -52.30 0.0090
2025-05-15 2025-03-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 4,333,613 2,758,171 175.07 108,904 216.22 0.0207
2025-02-14 2024-12-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 1,575,442 235,410 17.57 34,439 10.30 0.0060
2024-11-14 2024-09-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 1,340,032 1,227,857 1,094.59 31,223 885.85 0.0060
2024-08-14 2024-06-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 112,175 -499,570 -81.66 3,168 -80.80 0.0006
2024-05-15 2024-03-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 611,745 177,710 40.94 16,493 25.53 0.0032
2024-02-14 2023-12-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 434,035 188,222 76.57 13,138 67.34 0.0026
2023-11-14 2023-09-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 245,813 120,043 95.45 7,851 38.29 0.0017
2023-08-14 2023-06-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 125,770 -529,170 -80.80 5,677 -81.94 0.0012
2023-05-15 2023-03-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 654,940 504,633 335.73 31,431 596.59 0.0069
2023-02-14 2022-12-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 150,307 131,233 688.02 4,512 982.01 0.0011
2022-11-14 2022-09-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 19,074 -81,916 -81.11 417 -80.05 0.0001
2022-08-15 2022-06-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 100,990 100,990 2,090 0.0005
2022-02-14 2021-12-31 13F ALLEGRO MICROSYSTEMS Cmn 01749D105 0 -9,211 -100.00 0 -100.00
2021-11-15 2021-09-30 13F ALLEGRO MICROSYSTEMS Cmn 01749D105 9,211 -14,566 -61.26 294 -55.39 0.0001
2021-08-16 2021-06-30 13F ALLEGRO MICROSYSTEMS COM 01749D105 23,777 15,791 197.73 659 226.24 0.0001
2021-05-21 2021-03-31 13F/A-1 ALLEGRO MICROSYSTEMS COM 01749D105 7,986 7,986 202 0.0000
2021-05-17 2021-03-31 13F ALLEGRO MICROSYSTEMS COM 01749D105 7,986 7,986 202 0.0000
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 ALLEGRO MICROSYSTEMS COM Call 21,900 -84.67 691 -81.69 n/a n/a n/a
2026-02-17 2025-12-31 13F ALLEGRO MICROSYSTEMS COM Call 142,900 12.43 3,770 1.56 n/a n/a n/a
2025-11-14 2025-09-30 13F ALLEGRO MICROSYSTEMS COM Call 127,100 -4.15 3,711 -18.13 n/a n/a n/a
2025-08-14 2025-06-30 13F ALLEGRO MICROSYSTEMS COM Call 132,600 275.64 4,534 411.05 n/a n/a n/a
2025-05-15 2025-03-31 13F ALLEGRO MICROSYSTEMS COM Call 35,300 -74.64 887 -70.84 n/a n/a n/a
2025-02-14 2024-12-31 13F ALLEGRO MICROSYSTEMS COM Call 139,200 19.18 3,043 11.80 n/a n/a n/a
2024-11-14 2024-09-30 13F ALLEGRO MICROSYSTEMS COM Call 116,800 -37.87 2,721 -48.75 n/a n/a n/a
2024-08-14 2024-06-30 13F ALLEGRO MICROSYSTEMS COM Call 188,000 -36.87 5,309 -33.87 n/a n/a n/a
2024-05-15 2024-03-31 13F ALLEGRO MICROSYSTEMS COM Call 297,800 -44.78 8,029 -50.82 n/a n/a n/a
2024-02-14 2023-12-31 13F ALLEGRO MICROSYSTEMS COM Call 539,300 89.23 16,325 79.35 n/a n/a n/a
2023-11-14 2023-09-30 13F ALLEGRO MICROSYSTEMS COM Call 285,000 -18.85 9,103 -42.58 n/a n/a n/a
2023-08-14 2023-06-30 13F ALLEGRO MICROSYSTEMS COM Call 351,200 7.76 15,853 1.37 n/a n/a n/a
2023-05-15 2023-03-31 13F ALLEGRO MICROSYSTEMS COM Call 325,900 186.63 15,640 358.22 n/a n/a n/a
2023-02-14 2022-12-31 13F ALLEGRO MICROSYSTEMS COM Call 113,700 668.24 3,413 956.66 n/a n/a n/a
2022-11-14 2022-09-30 13F ALLEGRO MICROSYSTEMS COM Call 14,800 -38.84 323 -35.53 n/a n/a n/a
2022-08-15 2022-06-30 13F ALLEGRO MICROSYSTEMS COM Call 24,200 42.35 501 3.73 n/a n/a n/a
2022-05-16 2022-03-31 13F ALLEGRO MICROSYSTEMS COM Call 17,000 -65.66 483 -73.03 n/a n/a n/a
2022-02-14 2021-12-31 13F ALLEGRO MICROSYSTEMS COM Call 49,500 200.00 1,791 239.85 n/a n/a n/a
2021-11-15 2021-09-30 13F ALLEGRO MICROSYSTEMS Cmn Call 16,500 25.95 527 45.18 n/a n/a n/a
2021-08-16 2021-06-30 13F ALLEGRO MICROSYSTEMS COM Call 13,100 6.50 363 16.35 n/a n/a n/a
2021-05-21 2021-03-31 13F/A ALLEGRO MICROSYSTEMS COM Call 12,300 312 n/a n/a n/a
2021-05-17 2021-03-31 13F ALLEGRO MICROSYSTEMS COM Call 12,300 312 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 ALLEGRO MICROSYSTEMS COM Put 45,600 273.77 1,438 347.66 n/a n/a n/a
2026-02-17 2025-12-31 13F ALLEGRO MICROSYSTEMS COM Put 12,200 -69.04 322 -72.09 n/a n/a n/a
2025-11-14 2025-09-30 13F ALLEGRO MICROSYSTEMS COM Put 39,400 -73.92 1,150 -77.74 n/a n/a n/a
2025-08-14 2025-06-30 13F ALLEGRO MICROSYSTEMS COM Put 151,100 63.17 5,166 122.00 n/a n/a n/a
2025-05-15 2025-03-31 13F ALLEGRO MICROSYSTEMS COM Put 92,600 -47.18 2,327 -39.27 n/a n/a n/a
2025-02-14 2024-12-31 13F ALLEGRO MICROSYSTEMS COM Put 175,300 11.73 3,832 4.84 n/a n/a n/a
2024-11-14 2024-09-30 13F ALLEGRO MICROSYSTEMS COM Put 156,900 302.31 3,656 231.97 n/a n/a n/a
2024-08-14 2024-06-30 13F ALLEGRO MICROSYSTEMS COM Put 39,000 -80.39 1,101 -79.47 n/a n/a n/a
2024-05-15 2024-03-31 13F ALLEGRO MICROSYSTEMS COM Put 198,900 -53.87 5,362 -58.92 n/a n/a n/a
2024-02-14 2023-12-31 13F ALLEGRO MICROSYSTEMS COM Put 431,200 -9.60 13,052 -14.33 n/a n/a n/a
2023-11-14 2023-09-30 13F ALLEGRO MICROSYSTEMS COM Put 477,000 11.61 15,235 -21.03 n/a n/a n/a
2023-08-14 2023-06-30 13F ALLEGRO MICROSYSTEMS COM Put 427,400 261.59 19,293 240.13 n/a n/a n/a
2023-05-15 2023-03-31 13F ALLEGRO MICROSYSTEMS COM Put 118,200 -45.93 5,672 -13.56 n/a n/a n/a
2023-02-14 2022-12-31 13F ALLEGRO MICROSYSTEMS COM Put 218,600 -27.25 6,562 -0.06 n/a n/a n/a
2022-11-14 2022-09-30 13F ALLEGRO MICROSYSTEMS COM Put 300,500 7.67 6,566 13.70 n/a n/a n/a
2022-08-15 2022-06-30 13F ALLEGRO MICROSYSTEMS COM Put 279,100 -71.23 5,775 -79.04 n/a n/a n/a
2022-05-16 2022-03-31 13F ALLEGRO MICROSYSTEMS COM Put 970,100 27,551 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.