Who owns Allegro MicroSystems (ALGM)
Which tracked institutional funds hold ALGM, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ALGM company fundamentals →
Ownership as of the 2026-Q1 13F filings (latest filed 2026-05-18). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
The tracked-fund tape on ALGM is one-sided between 2025-Q4 and 2026-Q1: 115 added or opened and 36 trimmed or exited — on balance accumulating.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
ALGM’s largest tracked holder by dollar value, FMR LLC, sizes it at 0.1% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.1pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in ALGM divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2025-Q4 and 2026-Q1, across 320 tracked filers holding ALGM, 192 increased or opened the position and 129 reduced or closed it; over the same quarter, open-market insider Form 4 buying and selling roughly offset.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in ALGM between the 2025-Q4 and 2026-Q1 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 26
- VANGUARD PORTFOLIO MANAGEMENT LLC$250M
- VANGUARD CAPITAL MANAGEMENT LLC$172M
- VANGUARD FIDUCIARY TRUST CO$24M
- Aperture Investors, LLC$22M
- LORD, ABBETT & CO. LLC$17M
- JACOBS LEVY EQUITY MANAGEMENT, INC$10M
Full exits 13
- VANGUARD GROUP INC$375M
- Analog Century Management LP$50M
- Point72 Asset Management, L.P.$30M
- Alyeska Investment Group, L.P.$11M
- Squarepoint Ops LLC$9M
- TWO SIGMA ADVISERS, LP$2M
Largest adds
- FMR LLC$240M
- Invesco Ltd.$55M
- JPMORGAN CHASE & CO$49M
- Capital Research Global Investors$46M
- Pacer Advisors, Inc.$40M
- LOOMIS SAYLES & CO L P$31M
Largest trims
- BlackRock, Inc.$101M
- CITADEL ADVISORS LLC$57M
- MILLENNIUM MANAGEMENT LLC$35M
- ADAGE CAPITAL PARTNERS GP, L.L.C.$28M
- Schonfeld Strategic Advisors LLC$20M
- BALYASNY ASSET MANAGEMENT L.P.$14M
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| FMR LLC trimmed | 25,581,021 | $1.8B | 21.7% | 2026-Q2 |
| BlackRock, Inc. added | 13,889,324 | $967M | 11.8% | 2026-Q2 |
| Invesco Ltd. added | 13,678,393 | $952M | 11.6% | 2026-Q2 |
| Capital Research Global Investors trimmed | 12,006,396 | $836M | 10.2% | 2026-Q2 |
| STATE STREET CORP added | 5,676,421 | $395M | 4.8% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 3,710,288 | $258M | 3.1% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 7,920,042 | $250M | 3.0% | 2026-Q1 |
| JPMORGAN CHASE & CO added | 8,652,068 | $243M | 3.0% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 5,464,718 | $172M | 2.1% | 2026-Q1 |
| Pacer Advisors, Inc. added | 14,546,487 | $119M | 1.4% | 2026-Q1 |
| Clearbridge Investments, LLC trimmed | 2,863,710 | $90M | 1.1% | 2026-Q1 |
| NORGES BANK added | 1,294,958 | $90M | 1.1% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 2,456,820 | $77M | 0.9% | 2026-Q1 |
| MORGAN STANLEY added | 2,275,285 | $72M | 0.9% | 2026-Q1 |
| DIMENSIONAL FUND ADVISORS LP added | 2,170,487 | $68M | 0.8% | 2026-Q1 |
| NOMURA ASSET MANAGEMENT INTERNATIONAL INC. added | 2,080,641 | $66M | 0.8% | 2026-Q1 |
| WELLINGTON MANAGEMENT GROUP LLP added | 814,937 | $57M | 0.7% | 2026-Q2 |
| PRINCIPAL FINANCIAL GROUP INC added | 1,790,466 | $56M | 0.7% | 2026-Q1 |
| LOOMIS SAYLES & CO L P added | 1,674,108 | $53M | 0.6% | 2026-Q1 |
| ADAGE CAPITAL PARTNERS GP, L.L.C. trimmed | 1,464,737 | $46M | 0.6% | 2026-Q1 |
| VOYA INVESTMENT MANAGEMENT LLC added | 1,459,271 | $46M | 0.6% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. added | 1,723,370 | $45M | 0.6% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 1,437,215 | $45M | 0.6% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 1,390,606 | $44M | 0.5% | 2026-Q1 |
| SEGALL BRYANT & HAMILL, LLC trimmed | 1,048,340 | $35M | 0.4% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC added | 493,753 | $33M | 0.4% | 2026-Q2 |
| NORTHERN TRUST CORP added | 1,045,541 | $33M | 0.4% | 2026-Q1 |
| RAYMOND JAMES FINANCIAL INC added | 995,753 | $31M | 0.4% | 2026-Q1 |
| Nuveen, LLC added | 947,502 | $30M | 0.4% | 2026-Q1 |
| KENNEDY CAPITAL MANAGEMENT LLC added | 910,039 | $29M | 0.3% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 855,453 | $27M | 0.3% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 765,886 | $24M | 0.3% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP trimmed | 343,994 | $24M | 0.3% | 2026-Q2 |
| Bank of New York Mellon Corp trimmed | 743,292 | $23M | 0.3% | 2026-Q1 |
| Aperture Investors, LLC new | 709,674 | $22M | 0.3% | 2026-Q1 |
| SILVERCREST ASSET MANAGEMENT GROUP LLC added | 707,891 | $22M | 0.3% | 2026-Q1 |
| GW&K Investment Management, LLC trimmed | 659,576 | $21M | 0.3% | 2026-Q1 |
| BALYASNY ASSET MANAGEMENT L.P. added | 267,283 | $19M | 0.2% | 2026-Q2 |
| T. Rowe Price Investment Management, Inc. added | 561,344 | $18M | 0.2% | 2026-Q1 |
| LORD, ABBETT & CO. LLC new | 530,455 | $17M | 0.2% | 2026-Q1 |
| Lightrock Netherlands B.V. added | 507,990 | $16M | 0.2% | 2026-Q1 |
| Talos Eurisko Asset Management LP trimmed | 493,173 | $16M | 0.2% | 2026-Q1 |
| S SQUARED TECHNOLOGY, LLC | 457,451 | $14M | 0.2% | 2026-Q1 |
| UBS Group AG added | 435,381 | $14M | 0.2% | 2026-Q1 |
| FIRST TRUST ADVISORS LP trimmed | 414,897 | $13M | 0.2% | 2026-Q1 |
| AMERIPRISE FINANCIAL INC trimmed | 359,282 | $11M | 0.1% | 2026-Q1 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC added | 345,057 | $11M | 0.1% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 326,266 | $10M | 0.1% | 2026-Q1 |
| Allspring Global Investments Holdings, LLC trimmed | 307,624 | $10M | 0.1% | 2026-Q1 |
| Gotham Asset Management, LLC added | 312,246 | $10M | 0.1% | 2026-Q1 |
| RHUMBLINE ADVISERS added | 308,407 | $10M | 0.1% | 2026-Q1 |
| JACOBS LEVY EQUITY MANAGEMENT, INC new | 308,102 | $10M | 0.1% | 2026-Q1 |
| Man Group plc trimmed | 306,349 | $10M | 0.1% | 2026-Q1 |
| SIRIOS CAPITAL MANAGEMENT L P new | 298,421 | $9M | 0.1% | 2026-Q1 |
| FRONTIER CAPITAL MANAGEMENT CO LLC trimmed | 264,031 | $8M | 0.1% | 2026-Q1 |
| HRT FINANCIAL LP added | 261,772 | $8M | 0.1% | 2026-Q1 |
| PEREGRINE CAPITAL MANAGEMENT LLC trimmed | 259,764 | $8M | 0.1% | 2026-Q1 |
| Swiss National Bank added | 256,400 | $8M | 0.1% | 2026-Q1 |
| Pier Capital, LLC trimmed | 226,566 | $7M | 0.1% | 2026-Q1 |
| SEI INVESTMENTS CO added | 218,976 | $7M | 0.1% | 2026-Q1 |
| Granahan Investment Management, LLC added | 215,001 | $7M | 0.1% | 2026-Q1 |
| G2 Investment Partners Management LLC added | 208,569 | $7M | 0.1% | 2026-Q1 |
| Retirement Systems of Alabama added | 193,195 | $6M | 0.1% | 2026-Q1 |
| KETTLE HILL CAPITAL MANAGEMENT, LLC added | 181,531 | $6M | 0.1% | 2026-Q1 |
| Roubaix Capital, LLC new | 169,993 | $5M | 0.1% | 2026-Q1 |
| Legal & General Group Plc trimmed | 164,671 | $5M | 0.1% | 2026-Q1 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM added | 149,826 | $5M | 0.1% | 2026-Q1 |
| CASTLEARK MANAGEMENT LLC added | 147,420 | $5M | 0.1% | 2026-Q1 |
| TRILLIUM ASSET MANAGEMENT, LLC trimmed | 127,557 | $4M | 0.1% | 2026-Q1 |
| Quantinno Capital Management LP added | 133,902 | $4M | 0.1% | 2026-Q1 |
| Trexquant Investment LP added | 133,800 | $4M | 0.1% | 2026-Q1 |
| Walleye Capital LLC added | 130,668 | $4M | 0.1% | 2026-Q1 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added | 127,393 | $4M | 0.0% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 123,900 | $4M | 0.0% | 2026-Q1 |
| CANADA PENSION PLAN INVESTMENT BOARD added | 122,000 | $4M | 0.0% | 2026-Q1 |
| ArrowMark Colorado Holdings LLC trimmed | 120,784 | $4M | 0.0% | 2026-Q1 |
| VANGUARD ASSET MANAGEMENT, Ltd new | 116,069 | $4M | 0.0% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed | 115,383 | $4M | 0.0% | 2026-Q1 |
| CITIGROUP INC trimmed | 106,154 | $3M | 0.0% | 2026-Q1 |
| Russell Investments Group, Ltd. added | 96,083 | $3M | 0.0% | 2026-Q1 |
| Brevan Howard Capital Management LP added | 95,099 | $3M | 0.0% | 2026-Q1 |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 94,953 | $3M | 0.0% | 2026-Q1 |
| VANGUARD GROUP INC trimmed | 14,202,528 | $375M | 4.6% | 2025-Q4 stale |
| MACQUARIE GROUP LTD trimmed | 2,197,274 | $64M | 0.8% | 2025-Q3 stale |
| Analog Century Management LP added | 1,890,072 | $50M | 0.6% | 2025-Q4 stale |
| Kodai Capital Management LP new | 1,655,806 | $42M | 0.5% | 2025-Q1 stale |
| Point72 Asset Management, L.P. added | 1,119,265 | $30M | 0.4% | 2025-Q4 stale |
| Cinctive Capital Management LP new | 942,702 | $24M | 0.3% | 2025-Q1 stale |
| Oasis Management Co Ltd. new | 530,210 | $13M | 0.2% | 2025-Q1 stale |
| FIFTHDELTA Ltd new | 505,600 | $13M | 0.2% | 2025-Q1 stale |
| Alyeska Investment Group, L.P. trimmed | 400,000 | $11M | 0.1% | 2025-Q4 stale |
| Squarepoint Ops LLC added | 353,991 | $9M | 0.1% | 2025-Q4 stale |
| Cubist Systematic Strategies, LLC new | 273,675 | $8M | 0.1% | 2025-Q3 stale |
| WESTFIELD CAPITAL MANAGEMENT CO LP trimmed | 303,672 | $8M | 0.1% | 2025-Q1 stale |
| Meridiem Capital Partners LP trimmed | 249,920 | $6M | 0.1% | 2025-Q1 stale |
| Polar Asset Management Partners Inc. trimmed | 232,055 | $6M | 0.1% | 2025-Q1 stale |
| OSTERWEIS CAPITAL MANAGEMENT INC new | 179,290 | $5M | 0.1% | 2025-Q1 stale |
| TIG Advisors, LLC new | 161,253 | $4M | 0.0% | 2025-Q1 stale |
| Corebridge Financial, Inc. trimmed | 144,303 | $4M | 0.0% | 2025-Q1 stale |
| Susquehanna Portfolio Strategies, LLC | 115,830 | $3M | 0.0% | 2025-Q3 stale |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.