Who owns ATRC (ATRC)
Which tracked institutional funds hold ATRC, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See ATRC company fundamentals →
Ownership as of the 2026-Q1 13F filings. 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 ATRC is one-sided between 2025-Q4 and 2026-Q1: 30 added or opened and 99 trimmed or exited — on balance reducing.
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
ATRC’s largest tracked holder by dollar value, VANGUARD GROUP INC, sizes it at 0.0% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 0.0pp gap the other way — the median holder sizes ATRC more heavily than its largest holder by dollar value does.
Book-share is each fund’s reported value in ATRC 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 223 tracked filers holding ATRC, 117 increased or opened the position and 114 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 ATRC 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 16
- VANGUARD PORTFOLIO MANAGEMENT LLC$77M
- VANGUARD CAPITAL MANAGEMENT LLC$62M
- Divisadero Street Capital Management, LP$33M
- VANGUARD FIDUCIARY TRUST CO$10M
- ARROWSTREET CAPITAL, LIMITED PARTNERSHIP$8M
- Schonfeld Strategic Advisors LLC$3M
Full exits 19
- VANGUARD GROUP INC$178M
- Defilade Capital Management, L.P.$16M
- Point72 Asset Management, L.P.$11M
- TWO SIGMA ADVISERS, LP$11M
- OBERWEIS ASSET MANAGEMENT INC/$9M
- Susquehanna Portfolio Strategies, LLC$3M
Largest adds
- GOLDMAN SACHS GROUP INC$13M
- MORGAN STANLEY$7M
- TWO SIGMA INVESTMENTS, LP$6M
- MARSHALL WACE, LLP$6M
- First Eagle Investment Management, LLC$3M
- OSTERWEIS CAPITAL MANAGEMENT INC$2M
Largest trims
- WELLINGTON MANAGEMENT GROUP LLP$60M
- BlackRock, Inc.$46M
- Hood River Capital Management LLC$34M
- NOMURA ASSET MANAGEMENT INTERNATIONAL INC.$29M
- First Light Asset Management, LLC$26M
- Champlain Investment Partners, LLC$19M
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 |
|---|---|---|---|---|
| ALLIANCEBERNSTEIN L.P. trimmed | 3,258,872 | $129M | 7.3% | 2026-Q1 |
| BlackRock, Inc. trimmed | 4,042,681 | $115M | 6.5% | 2026-Q1 |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 3,340,469 | $95M | 5.4% | 2026-Q1 |
| Hood River Capital Management LLC added | 3,117,545 | $89M | 5.0% | 2026-Q1 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 2,702,632 | $77M | 4.3% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 2,155,764 | $62M | 3.5% | 2026-Q1 |
| NOMURA ASSET MANAGEMENT INTERNATIONAL INC. trimmed | 1,804,927 | $51M | 2.9% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC added | 1,667,166 | $48M | 2.7% | 2026-Q1 |
| MARSHALL WACE, LLP added | 1,467,524 | $42M | 2.4% | 2026-Q1 |
| STATE STREET CORP added | 1,302,162 | $37M | 2.1% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,226,116 | $35M | 2.0% | 2026-Q1 |
| Divisadero Street Capital Management, LP added | 1,159,955 | $33M | 1.9% | 2026-Q1 |
| BNP PARIBAS ASSET MANAGEMENT Holding S.A. added | 1,060,806 | $30M | 1.7% | 2026-Q1 |
| NEUBERGER BERMAN GROUP LLC trimmed | 1,050,282 | $30M | 1.7% | 2026-Q1 |
| DIMENSIONAL FUND ADVISORS LP added | 997,759 | $28M | 1.6% | 2026-Q1 |
| Champlain Investment Partners, LLC trimmed | 971,111 | $28M | 1.6% | 2026-Q1 |
| GW&K Investment Management, LLC added | 963,415 | $27M | 1.5% | 2026-Q1 |
| KENNEDY CAPITAL MANAGEMENT LLC trimmed | 834,155 | $24M | 1.3% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ added | 768,561 | $22M | 1.2% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP added | 751,003 | $21M | 1.2% | 2026-Q1 |
| First Light Asset Management, LLC trimmed | 729,521 | $21M | 1.2% | 2026-Q1 |
| VOYA INVESTMENT MANAGEMENT LLC added | 719,649 | $21M | 1.2% | 2026-Q1 |
| MORGAN STANLEY added | 719,162 | $21M | 1.2% | 2026-Q1 |
| DAFNA Capital Management LLC | 597,431 | $17M | 1.0% | 2026-Q1 |
| MASSACHUSETTS FINANCIAL SERVICES CO /MA/ added | 585,353 | $17M | 0.9% | 2026-Q1 |
| UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC trimmed | 555,114 | $16M | 0.9% | 2026-Q1 |
| Qube Research & Technologies Ltd added | 454,791 | $13M | 0.7% | 2026-Q1 |
| NORTHERN TRUST CORP added | 449,599 | $13M | 0.7% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 429,833 | $12M | 0.7% | 2026-Q1 |
| Grandeur Peak Global Advisors, LLC added | 381,902 | $11M | 0.6% | 2026-Q1 |
| WCM INVESTMENT MANAGEMENT, LLC trimmed | 359,761 | $10M | 0.6% | 2026-Q1 |
| OSTERWEIS CAPITAL MANAGEMENT INC added | 349,645 | $10M | 0.6% | 2026-Q1 |
| Connor, Clark & Lunn Investment Management Ltd. trimmed | 345,388 | $10M | 0.6% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 342,854 | $10M | 0.6% | 2026-Q1 |
| Nuveen, LLC added | 336,727 | $10M | 0.5% | 2026-Q1 |
| FMR LLC added | 336,265 | $10M | 0.5% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC trimmed | 308,700 | $9M | 0.5% | 2026-Q1 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP added | 277,682 | $8M | 0.4% | 2026-Q1 |
| First Eagle Investment Management, LLC added | 262,143 | $7M | 0.4% | 2026-Q1 |
| SEI INVESTMENTS CO added | 260,788 | $7M | 0.4% | 2026-Q1 |
| WASATCH ADVISORS LP trimmed | 253,931 | $7M | 0.4% | 2026-Q1 |
| PANAGORA ASSET MANAGEMENT INC added | 227,377 | $6M | 0.4% | 2026-Q1 |
| Amundi trimmed | 225,932 | $6M | 0.4% | 2026-Q1 |
| Universal- Beteiligungs- und Servicegesellschaft mbH added | 215,545 | $6M | 0.3% | 2026-Q1 |
| RAYMOND JAMES FINANCIAL INC trimmed | 216,907 | $6M | 0.3% | 2026-Q1 |
| NICHOLAS COMPANY, INC. trimmed | 204,595 | $6M | 0.3% | 2026-Q1 |
| FIRST TRUST ADVISORS LP added | 189,285 | $5M | 0.3% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC added | 184,678 | $5M | 0.3% | 2026-Q1 |
| Advisors Capital Management, LLC trimmed | 182,314 | $5M | 0.3% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC added | 179,886 | $5M | 0.3% | 2026-Q1 |
| JPMORGAN CHASE & CO trimmed | 171,263 | $5M | 0.3% | 2026-Q1 |
| STATE OF WISCONSIN INVESTMENT BOARD added | 167,354 | $5M | 0.3% | 2026-Q1 |
| ADAGE CAPITAL PARTNERS GP, L.L.C. added | 150,000 | $4M | 0.2% | 2026-Q1 |
| Trexquant Investment LP added | 143,094 | $4M | 0.2% | 2026-Q1 |
| Bank of New York Mellon Corp trimmed | 130,650 | $4M | 0.2% | 2026-Q1 |
| PARADIGM CAPITAL MANAGEMENT INC/NY | 123,100 | $4M | 0.2% | 2026-Q1 |
| Allianz Asset Management GmbH added | 122,158 | $3M | 0.2% | 2026-Q1 |
| SIT INVESTMENT ASSOCIATES INC added | 113,330 | $3M | 0.2% | 2026-Q1 |
| Schonfeld Strategic Advisors LLC added | 101,682 | $3M | 0.2% | 2026-Q1 |
| Swiss National Bank | 98,000 | $3M | 0.2% | 2026-Q1 |
| VOLORIDGE INVESTMENT MANAGEMENT, LLC trimmed | 97,182 | $3M | 0.2% | 2026-Q1 |
| ACADIAN ASSET MANAGEMENT LLC added | 88,852 | $3M | 0.1% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 87,347 | $2M | 0.1% | 2026-Q1 |
| Man Group plc added | 85,116 | $2M | 0.1% | 2026-Q1 |
| HighMark Wealth Management LLC | 83,720 | $2M | 0.1% | 2026-Q1 |
| Invesco Ltd. added | 77,316 | $2M | 0.1% | 2026-Q1 |
| Emerald Investment Advisers, LLC new | 71,492 | $2M | 0.1% | 2026-Q1 |
| Riverwater Partners LLC added | 70,506 | $2M | 0.1% | 2026-Q1 |
| WELLS FARGO & COMPANY/MN trimmed | 69,084 | $2M | 0.1% | 2026-Q1 |
| HRT FINANCIAL LP added | 67,071 | $2M | 0.1% | 2026-Q1 |
| NORGES BANK trimmed | 58,954 | $2M | 0.1% | 2026-Q1 |
| RHUMBLINE ADVISERS trimmed | 66,281 | $2M | 0.1% | 2026-Q1 |
| UBS Group AG trimmed | 65,865 | $2M | 0.1% | 2026-Q1 |
| PRINCIPAL FINANCIAL GROUP INC added | 64,296 | $2M | 0.1% | 2026-Q1 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 60,285 | $2M | 0.1% | 2026-Q1 |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM added | 59,947 | $2M | 0.1% | 2026-Q1 |
| Orion Porfolio Solutions, LLC trimmed | 58,297 | $2M | 0.1% | 2026-Q1 |
| ENVESTNET ASSET MANAGEMENT INC trimmed | 57,877 | $2M | 0.1% | 2026-Q1 |
| D. E. Shaw & Co., Inc. added | 56,589 | $2M | 0.1% | 2026-Q1 |
| FRANKLIN RESOURCES INC added | 55,516 | $2M | 0.1% | 2026-Q1 |
| LAZARD ASSET MANAGEMENT LLC added | 54,015 | $2M | 0.1% | 2026-Q1 |
| VANGUARD GROUP INC trimmed | 4,488,601 | $178M | 10.0% | 2025-Q4 stale |
| MACQUARIE GROUP LTD trimmed | 2,289,369 | $81M | 4.5% | 2025-Q3 stale |
| JENNISON ASSOCIATES LLC new | 593,270 | $19M | 1.1% | 2025-Q1 stale |
| Defilade Capital Management, L.P. new | 397,636 | $16M | 0.9% | 2025-Q4 stale |
| Point72 Asset Management, L.P. trimmed | 277,924 | $11M | 0.6% | 2025-Q4 stale |
| TWO SIGMA ADVISERS, LP trimmed | 277,700 | $11M | 0.6% | 2025-Q4 stale |
| Point72 (DIFC) Ltd added | 262,065 | $9M | 0.5% | 2025-Q3 stale |
| OBERWEIS ASSET MANAGEMENT INC/ added | 217,992 | $9M | 0.5% | 2025-Q4 stale |
| Susquehanna Portfolio Strategies, LLC added | 86,325 | $3M | 0.2% | 2025-Q4 stale |
| Squarepoint Ops LLC trimmed | 85,803 | $3M | 0.2% | 2025-Q4 stale |
| DARK FOREST CAPITAL MANAGEMENT LP added | 95,574 | $3M | 0.2% | 2025-Q1 stale |
| F/m Investments LLC new | 72,588 | $3M | 0.2% | 2025-Q4 stale |
| Informed Momentum Co LLC added | 85,525 | $3M | 0.2% | 2025-Q1 stale |
| SUSQUEHANNA FUNDAMENTAL INVESTMENTS, LLC trimmed | 75,922 | $3M | 0.2% | 2025-Q3 stale |
| M&T Bank Corp added | 13,431 | $2M | 0.1% | 2025-Q4 stale |
| JANE STREET GROUP, LLC trimmed | 52,620 | $2M | 0.1% | 2025-Q4 stale |
| DEERFIELD MANAGEMENT COMPANY, L.P. trimmed | 52,076 | $2M | 0.1% | 2025-Q4 stale |
| Orion Portfolio Solutions, LLC added | 63,706 | $2M | 0.1% | 2025-Q1 stale |
| OpenArc Corporate Advisory, LLC new | 44,084 | $2M | 0.1% | 2025-Q4 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.