Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
216 institutional managers reported holding ADTN for the quarter ended Mar 31, 2026. Reported positions total over 95% of shares outstanding; the top 10 hold 43%. 42 opened new positions; 36 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| Vanguard Group | 8.85M | 11.02% | $111.1M | added +8% | ≤2013 |
| BlackRock | 7.84M | 9.76% | $98.5M | trimmed -3.5% | ≤2013 |
| Royce & Associates | 3.13M | 3.89% | $39.3M | added +20.4% | 2024 Q4 |
| DNB Asset Management AS | 3.12M | 3.89% | $39.2M | unchanged | 2022 Q1 |
| State Street | 2.35M | 2.93% | $29.5M | added +18.4% | ≤2013 |
| William Blair Investment Management, LLC | 1.99M | 2.48% | $25.0M | trimmed -19.7% | 2023 Q2 |
| Millennium Management | 1.90M | 2.36% | $23.8M | trimmed -29.6% | ≤2013 |
| Morgan Stanley | 1.83M | 2.28% | $23.0M | added +36.4% | ≤2013 |
| Geode Capital | 1.82M | 2.27% | $22.8M | added +3% | ≤2013 |
| Divisar Capital Management LLC (focused) | 1.77M | 2.20% | $22.2M | trimmed -40.7% | 2023 Q2 |
| First Eagle Investment Management | 1.37M | 1.70% | $17.2M | added +10.8% | 2021 Q2 |
| Dimensional Fund Advisors | 1.34M | 1.67% | $16.8M | added +50.5% | ≤2013 |
| SG Americas Securities, LLC | 1.32M | 1.64% | $16.5M | added +53.6% | 2016 Q3 |
| Needham Investment Management LLC | 1.23M | 1.53% | $15.4M | trimmed -15.1% | 2020 Q2 |
| Shannon River Fund Management LLC (focused) | 1.22M | 1.52% | $15.3M | opened | 2026 Q1 |
| D. E. Shaw | 1.22M | 1.52% | $15.3M | added +1.7% | 2023 Q2 |
| Boston Partners | 1.18M | 1.47% | $14.8M | opened | 2026 Q1 |
| Two Sigma | 1.12M | 1.40% | $14.1M | added +1492.9% | 2023 Q4 |
| SEI Investments CO | 1.11M | 1.38% | $13.9M | added +162% | 2025 Q4 |
| Tieton Capital Management, LLC (focused) | 1.04M | 1.29% | $13.0M | added +4.7% | ≤2013 |
| Invesco | 991.0k | 1.23% | $12.4M | added +301.5% | ≤2013 |
| Goldman Sachs | 970.7k | 1.21% | $12.2M | added +86.2% | ≤2013 |
| Barclays PLC | 927.8k | 1.16% | $11.7M | trimmed -17.6% | ≤2013 |
| Federated Hermes, INC. | 922.6k | 1.15% | $11.6M | added +6.5% | 2023 Q4 |
| Marshall Wace | 891.5k | 1.11% | $11.2M | opened | 2023 Q3 |
| Squarepoint Ops LLC | 888.0k | 1.11% | $11.2M | added +11.4% | 2021 Q3 |
| AQR Capital | 843.9k | 1.05% | $10.6M | added +256.2% | 2024 Q2 |
| Westerly Capital Management, LLC (focused) | 800.0k | 1.00% | $10.0M | added +14.3% | 2024 Q2 |
| Heartland Advisors INC | 750.0k | 0.93% | $9.4M | opened | 2026 Q1 |
| Kovack Advisors, INC. | 736.0k | 0.92% | $9.2M | trimmed -2.3% | 2023 Q2 |
| Paradigm Capital Management INC/NY | 733.2k | 0.91% | $9.2M | trimmed -35.1% | 2023 Q2 |
| Trexquant Investment LP | 684.9k | 0.85% | $8.6M | added +90.8% | 2024 Q2 |
| Northern Trust | 659.2k | 0.82% | $8.3M | added +2.6% | ≤2013 |
| Tudor Investment | 654.9k | 0.81% | $8.2M | trimmed -30.9% | 2022 Q3 |
| 1492 Capital Management LLC | 625.0k | 0.78% | $7.9M | added +6.8% | 2024 Q4 |
| Charles Schwab Investment Management | 624.1k | 0.78% | $7.8M | trimmed -9.1% | ≤2013 |
| FMR (Fidelity) | 615.4k | 0.77% | $7.7M | added +211% | ≤2013 |
| HRT Financial LP | 568.1k | 0.71% | $7.1M | added +4% | 2020 Q2 |
| Point72 | 564.8k | 0.70% | $7.1M | added +34% | 2023 Q4 |
| Connor, Clark & Lunn Investment Management LTD. | 560.3k | 0.70% | $7.0M | added +53.4% | 2024 Q4 |
| Kerrisdale Advisers, LLC | 552.0k | 0.69% | $6.9M | opened | 2026 Q1 |
| Nomura Asset Management International INC. | 464.2k | 0.58% | $5.8M | trimmed -31.9% | 2025 Q4 |
| Jacobs Levy Equity Management, INC | 461.7k | 0.57% | $5.8M | added +680% | 2025 Q1 |
| Assenagon Asset Management S.a. | 458.0k | 0.57% | $5.8M | trimmed -59.4% | 2024 Q2 |
| Royal Bank OF Canada | 457.4k | 0.57% | $5.7M | trimmed -14.6% | ≤2013 |
| Arrowstreet Capital | 455.6k | 0.57% | $5.7M | added +60.2% | 2024 Q2 |
| UBS | 439.4k | 0.55% | $5.5M | added +23.4% | ≤2013 |
| Citadel Advisors | 393.7k | 0.49% | $4.9M | added +300.2% | ≤2013 |
| Wells Fargo & COMPANY/MN | 378.6k | 0.47% | $4.8M | trimmed -11% | ≤2013 |
| Mackenzie Financial CORP | 368.7k | 0.46% | $4.6M | added +2% | 2025 Q1 |
Largest 50 of 216 shown; the full ranked, searchable register is at boothcheck.com/holders/ADTN. Related filers are grouped using the filings' own included-manager declarations. Historically, several managers opening new positions in the same quarter said almost nothing about the quarter that followed (59,118 cases since 2013). A filed record, not a forecast. Nothing here is investment advice.