This stock page is the public Follow view. For one current, evidence-backed answer, use capital_change_brief through REST or MCP. It compares tracked 13F changes with qualifying Form 4 activity and cites the SEC evidence.
curl -H "Authorization: Bearer YOUR_API_KEY" \ "https://arkolith.com/api/v1/stocks/MGNI/capital-change-brief"
Use Arkolith's capital_change_brief for MGNI. Tell me what changed, whether insider activity corroborates it, and cite the SEC evidence.
| # | Fund | Position value | Shares | Last move | As of | History |
|---|---|---|---|---|---|---|
| 1 | BlackRock, Inc. | $138.5M | 11.7M | ▲+0.6% Added · +64K sh | Q1 2026 | |
| 2 | VANGUARD PORTFOLIO MANAGEMENT LLC | $91.8M | 7.7M | ▲New +7.7M sh | Q1 2026 | |
| 3 | VANGUARD CAPITAL MANAGEMENT LLC | $73.5M | 6.2M | ▲New +6.2M sh | Q1 2026 | |
| 4 | Boston Partners | $56.1M | 4.7M | ▲+15% Added · +611K sh | Q1 2026 | |
| 5 | AMERICAN CENTURY COMPANIES INC | $55.0M | 4.6M | ▼−12% Reduced · −660K sh | Q1 2026 | |
| 6 | FMR LLC | $53.5M | 4.5M | ▼−33% Reduced · −2.2M sh | Q1 2026 | |
| 7 | DIMENSIONAL FUND ADVISORS LP | $47.3M | 4.0M | ▲+10% Added · +368K sh | Q1 2026 | |
| 8 | Nuveen, LLC | $42.6M | 3.6M | ▲+1.7% Added · +59K sh | Q1 2026 | |
| 9 | GEODE CAPITAL MANAGEMENT, LLC | $42.2M | 3.6M | ▲+3.5% Added · +120K sh | Q1 2026 | |
| 10 | Nine Ten Capital Management LLC | $41.4M | 3.5M | ▲+16% Added · +478K sh | Q1 2026 | |
| 11 | STATE STREET CORP | $37.6M | 3.2M | ▲+0.7% Added · +21K sh | Q1 2026 | |
| 12 | Granahan Investment Management, LLC | $30.3M | 2.6M | ▼−18% Reduced · −563K sh | Q1 2026 | |
| 13 | Ophir Asset Management Pty Ltd | $25.2M | 2.1M | ▼−11% Reduced · −266K sh | Q1 2026 | |
| 14 | 325 CAPITAL LLC | $23.8M | 2.0M | —Held | Q1 2026 | |
| 15 | KENNEDY CAPITAL MANAGEMENT LLC | $20.8M | 1.8M | ▲+22% Added · +318K sh | Q1 2026 | |
| 16 | JANE STREET GROUP, LLC | $19.8M | 1.7M | ▲+339% Added · +1.3M sh | Q1 2026 | |
| 17 | No Street GP LP | $19.3M | 1.6M | ▲+10% Added · +153K sh | Q1 2026 | |
| 18 | Schonfeld Strategic Advisors LLC | $19.1M | 1.6M | ▲+106% Added · +825K sh | Q1 2026 | |
| 19 | GOLDMAN SACHS GROUP INC | $17.8M | 1.5M | ▼−15% Reduced · −260K sh | Q1 2026 | |
| 20 | BALYASNY ASSET MANAGEMENT L.P. | $17.8M | 1.5M | ▲+72% Added · +627K sh | Q1 2026 | |
| 21 | Blue Grotto Capital, LLC | $15.8M | 1.3M | ▼−18% Reduced · −300K sh | Q1 2026 | |
| 22 | NORTHERN TRUST CORP | $15.7M | 1.3M | ▲+4.0% Added · +51K sh | Q1 2026 | |
| 23 | VICTORY CAPITAL MANAGEMENT INC | $15.0M | 1.3M | ▲+738% Added · +1.1M sh | Q1 2026 | |
| 24 | GRIZZLYROCK CAPITAL, LLC | $14.7M | 1.2M | ▲+117% Added · +667K sh | Q1 2026 | |
| 25 | MILLENNIUM MANAGEMENT LLC | $14.7M | 1.2M | ▲52× Added · +1.2M sh | Q1 2026 |
Holders and values reflect the 13F filers Arkolith currently tracks, not the entire institutional universe. Counts and totals are a floor, not the full institutional ownership.
| Date | Insider | Role | Action | Shares | Value |
|---|---|---|---|---|---|
| Jul 15, 2026 | BARRETT MICHAEL G. | CEO, Director | Option exercise (M) | 39K | $0 |
| Jul 15, 2026 | BARRETT MICHAEL G. | CEO, Director | Sell (S) | 39K | $785K |
| Jul 15, 2026 | BARRETT MICHAEL G. | CEO, Director | Option exercise (M) | 39K | $224K |
| Jul 10, 2026 | Caine Paul | Director | Sell (S) | 5K | $103K |
| Jul 7, 2026 | Buckley Sean Patrick | See Remarks | Sell (S) | 19K | $404K |
| Jul 7, 2026 | Buonasera David | CHIEF TECHNOLOGY OFFICER | Sell (S) | 1K | $26K |
| Jul 1, 2026 | Buonasera David | CHIEF TECHNOLOGY OFFICER | Sell (S) | 9K | $188K |
| Jun 29, 2026 | BARRETT MICHAEL G. | CEO, Director | Option exercise (M) | 75K | $435K |
| Jun 29, 2026 | BARRETT MICHAEL G. | CEO, Director | Sell (S) | 75K | $1.5M |
| Jun 29, 2026 | BARRETT MICHAEL G. | CEO, Director | Option exercise (M) | 75K | $0 |
| Jun 17, 2026 | Buonasera David | CHIEF TECHNOLOGY OFFICER | Sell (S) | 1K | $27K |
| Jun 17, 2026 | Buckley Sean Patrick | See Remarks | Sell (S) | 19K | $365K |
| Company | Co-held by | Combined value |
|---|---|---|
| MICROSOFT CORPMSFT | 87 funds | $31.3B |
| NVIDIA CORPNVDA | 84 funds | $48.5B |
| APPLE INCAAPL | 83 funds | $36.9B |
| ALPHABET INC-CL AGOOGL | 83 funds | $21.5B |
| META PLATFORMS INC-CLASS AMETA | 83 funds | $17.1B |
| AMAZON.COM INCAMZN | 82 funds | $25.9B |
| TESLA INCTSLA | 82 funds | $10.3B |
| ELI LILLY & COLLY | 82 funds | $8.5B |
| BROADCOM INCAVGO | 81 funds | $17.3B |
| MICRON TECHNOLOGY INCMU | 81 funds | $6.6B |
| MASTERCARD INC - AMA | 80 funds | $5.7B |
| LAM RESEARCH CORPLRCX | 80 funds | $3.7B |
Ranked by how many of MGNI's institutional holders also hold each name, a cross-fund conviction signal. Via the MCP server (ticker.co_held).
13F holdings + Form 4 insider transactions + end-of-day price history + the live filing stream, joined for MGNI. Filings are public domain, sourced to SEC EDGAR; price series derived from end-of-day closes. Every panel above is one call to the Arkolith API & MCP server.