Mar 31, 2026 filings. Quarterly 13F reports arrive up to 45 days after quarter end; this register is filed through May 29, 2026.
283 institutional managers reported holding ALRM for the quarter ended Mar 31, 2026. Together they hold about 85% of shares outstanding; the top 10 hold 52%. 29 opened new positions; 48 closed out. Complete ranked register from SEC 13F filings.
| manager | shares | % out | value (Mar 31, 2026 close) | change | held since |
|---|---|---|---|---|---|
| BlackRock | 9.14M | 16.22% | $394.5M | trimmed -1.2% | 2015 Q3 |
| Vanguard Group | 6.53M | 11.60% | $282.1M | added +3.9% | 2015 Q2 |
| Disciplined Growth Investors INC /MN | 3.27M | 5.80% | $141.2M | trimmed -4.3% | 2020 Q1 |
| Bank OF Montreal /CAN/ | 2.66M | 4.72% | $114.8M | added +19.1% | 2015 Q4 |
| State Street | 2.04M | 3.62% | $87.9M | added +0.7% | 2015 Q3 |
| Morgan Stanley | 1.26M | 2.24% | $54.5M | trimmed -5.6% | 2015 Q2 |
| Geode Capital | 1.26M | 2.23% | $54.2M | added +3% | 2015 Q3 |
| Dimensional Fund Advisors | 1.12M | 1.98% | $48.2M | added +1.1% | 2018 Q2 |
| Geneva Capital Management LLC | 1.07M | 1.90% | $46.2M | trimmed -7.3% | 2020 Q1 |
| FMR (Fidelity) | 969.1k | 1.72% | $41.8M | added +20.6% | 2016 Q3 |
| Arrowstreet Capital | 779.2k | 1.38% | $33.6M | added +43.9% | 2019 Q1 |
| Two Sigma | 681.3k | 1.21% | $29.4M | added +120% | 2022 Q4 |
| Northern Trust | 642.2k | 1.14% | $27.7M | unchanged | 2015 Q3 |
| T. Rowe Price | 629.5k | 1.12% | $27.2M | trimmed -29.7% | 2016 Q3 |
| Riverbridge Partners LLC | 592.9k | 1.05% | $25.6M | trimmed -18% | 2017 Q2 |
| Charles Schwab Investment Management | 579.6k | 1.03% | $25.0M | added +1.9% | 2015 Q4 |
| Goldman Sachs | 565.1k | 1.00% | $24.4M | trimmed -4.3% | 2015 Q2 |
| Algert Global LLC | 525.8k | 0.93% | $22.7M | added +19.9% | 2021 Q3 |
| SG Americas Securities, LLC | 483.5k | 0.86% | $20.9M | added +85.3% | 2023 Q4 |
| BNP Paribas Financial Markets | 458.4k | 0.81% | $19.8M | trimmed -23.9% | 2023 Q4 |
| Select Equity Group | 392.4k | 0.70% | $16.9M | added +14% | 2023 Q3 |
| Acadian Asset Management | 380.9k | 0.68% | $16.4M | added +86.5% | 2023 Q1 |
| Brown Capital Management LLC | 359.2k | 0.64% | $15.5M | trimmed -28.8% | 2018 Q1 |
| Deutsche Bank AG\ | 356.8k | 0.63% | $15.4M | trimmed -14.4% | 2015 Q2 |
| Nuveen | 351.0k | 0.62% | $15.2M | added +10.9% | 2018 Q4 |
| Qube Research & Technologies LTD | 349.2k | 0.62% | $15.1M | trimmed -9.5% | 2022 Q4 |
| Bank OF America CORP /DE/ | 341.9k | 0.61% | $14.8M | trimmed -4.1% | 2015 Q2 |
| Principal Financial Group INC | 300.2k | 0.53% | $13.0M | added +5.2% | 2017 Q4 |
| DF Dent & CO INC | 300.0k | 0.53% | $13.0M | trimmed -26.9% | 2020 Q2 |
| BNY Mellon | 289.8k | 0.52% | $12.5M | trimmed -1.7% | 2015 Q3 |
| American Century Companies INC | 288.4k | 0.51% | $12.5M | added +195% | 2020 Q4 |
| Public Sector Pension Investment Board | 281.6k | 0.50% | $12.2M | trimmed -3.5% | 2017 Q4 |
| Centaurus Financial, INC. | 271.8k | 0.48% | $11.7M | added +1% | 2017 Q4 |
| Invesco | 269.2k | 0.48% | $11.6M | added +10.4% | 2016 Q1 |
| Nomura Asset Management International INC. | 249.0k | 0.44% | $10.8M | trimmed -13.6% | 2024 Q2 |
| Wells Fargo & COMPANY/MN | 241.2k | 0.43% | $10.4M | trimmed -30.3% | 2015 Q3 |
| UBS | 239.4k | 0.42% | $10.3M | added +61.7% | 2015 Q2 |
| D. E. Shaw | 238.5k | 0.42% | $10.3M | trimmed -15% | 2021 Q2 |
| Tudor Investment | 238.2k | 0.42% | $10.3M | added +9.5% | 2022 Q3 |
| Federated Hermes, INC. | 220.8k | 0.39% | $9.5M | added +273% | 2015 Q2 |
| Summit Creek Advisors LLC | 191.4k | 0.34% | $8.3M | trimmed -11.3% | 2016 Q4 |
| Handelsbanken Fonder AB | 190.8k | 0.34% | $8.2M | trimmed -29.9% | 2018 Q4 |
| AQR Capital | 165.1k | 0.29% | $7.1M | added +21.7% | 2020 Q3 |
| Voloridge Investment Management | 164.9k | 0.29% | $7.1M | trimmed -24.8% | 2025 Q2 |
| Evanson Asset Management, LLC | 162.5k | 0.29% | $7.0M | trimmed -3.8% | 2016 Q2 |
| Jacobs Levy Equity Management, INC | 154.7k | 0.28% | $6.7M | added +4.6% | 2024 Q4 |
| Connor, Clark & Lunn Investment Management LTD. | 143.2k | 0.25% | $6.2M | trimmed -48.9% | 2022 Q4 |
| Montanaro Asset Management LTD (focused) | 141.7k | 0.25% | $6.1M | trimmed -5.6% | 2020 Q4 |
| Mercer Global Advisors INC /ADV | 139.9k | 0.25% | $6.0M | unchanged | 2024 Q4 |
| Jane Street | 133.2k | 0.24% | $5.7M | trimmed -3.7% | 2018 Q2 |
Largest 50 of 283 shown; the full ranked, searchable register is at boothcheck.com/holders/ALRM. 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.