Who owns 908 Devices Inc. (MASS)
Which tracked institutional funds hold MASS, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MASS 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 MASS is one-sided between 2025-Q4 and 2026-Q1: 21 added or opened and 6 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
MASS’s largest tracked holder by dollar value, First Light Asset Management, LLC, sizes it at 3.3% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 3.3pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MASS 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 112 tracked filers holding MASS, 43 increased or opened the position and 63 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 MASS 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 3
- VANGUARD CAPITAL MANAGEMENT LLC$7M
- VANGUARD FIDUCIARY TRUST CO$1M
- VANGUARD PORTFOLIO MANAGEMENT LLC$1M
Full exits 3
- VANGUARD GROUP INC$8M
- MARSHALL WACE, LLP$1M
- HRT FINANCIAL LP$812K
Largest adds
- First Light Asset Management, LLC$12M
- AWM Investment Company, Inc.$5M
- Granahan Investment Management, LLC$4M
- NEEDHAM INVESTMENT MANAGEMENT LLC$4M
- First Eagle Investment Management, LLC$2M
- ARK Investment Management LLC$1M
Largest trims
- DIMENSIONAL FUND ADVISORS LP$569K
- CITADEL ADVISORS LLC$503K
- GOLDMAN SACHS GROUP INC$366K
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 |
|---|---|---|---|---|
| First Light Asset Management, LLC added | 6,072,563 | $37M | 19.9% | 2026-Q1 |
| AWM Investment Company, Inc. | 5,199,924 | $32M | 17.1% | 2026-Q1 |
| ARK Investment Management LLC trimmed | 1,946,685 | $12M | 6.4% | 2026-Q1 |
| BlackRock, Inc. trimmed | 1,767,316 | $11M | 5.8% | 2026-Q1 |
| NEEDHAM INVESTMENT MANAGEMENT LLC added | 1,240,000 | $8M | 4.1% | 2026-Q1 |
| VANGUARD CAPITAL MANAGEMENT LLC new | 1,119,236 | $7M | 3.7% | 2026-Q1 |
| First Eagle Investment Management, LLC added | 803,606 | $5M | 2.6% | 2026-Q1 |
| GEODE CAPITAL MANAGEMENT, LLC added | 695,455 | $4M | 2.3% | 2026-Q1 |
| Granahan Investment Management, LLC added | 695,070 | $4M | 2.3% | 2026-Q1 |
| STATE STREET CORP added | 625,892 | $4M | 2.1% | 2026-Q1 |
| Tao Capital Management LP | 568,981 | $3M | 1.9% | 2026-Q1 |
| ESSEX INVESTMENT MANAGEMENT CO LLC added | 491,221 | $3M | 1.6% | 2026-Q1 |
| MORGAN STANLEY trimmed | 373,258 | $2M | 1.2% | 2026-Q1 |
| Meros Investment Management, LP added | 361,738 | $2M | 1.2% | 2026-Q1 |
| Prescott Group Capital Management, L.L.C. | 361,595 | $2M | 1.2% | 2026-Q1 |
| HighMark Wealth Management LLC added | 319,350 | $2M | 1.0% | 2026-Q1 |
| Amova Asset Management Americas, Inc. trimmed | 269,873 | $2M | 0.9% | 2026-Q1 |
| Sumitomo Mitsui Trust Group, Inc. trimmed | 269,873 | $2M | 0.9% | 2026-Q1 |
| GSA CAPITAL PARTNERS LLP added | 251,028 | $2M | 0.8% | 2026-Q1 |
| NORTHERN TRUST CORP added | 241,332 | $1M | 0.8% | 2026-Q1 |
| GM Advisory Group, LLC trimmed | 238,218 | $1M | 0.8% | 2026-Q1 |
| RENAISSANCE TECHNOLOGIES LLC added | 230,200 | $1M | 0.8% | 2026-Q1 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC trimmed | 229,489 | $1M | 0.8% | 2026-Q1 |
| Squarepoint Ops LLC trimmed | 213,193 | $1M | 0.7% | 2026-Q1 |
| VANGUARD FIDUCIARY TRUST CO new | 180,250 | $1M | 0.6% | 2026-Q1 |
| RAYMOND JAMES FINANCIAL INC trimmed | 176,520 | $1M | 0.6% | 2026-Q1 |
| SEI INVESTMENTS CO added | 164,894 | $1M | 0.5% | 2026-Q1 |
| VANGUARD PORTFOLIO MANAGEMENT LLC new | 163,694 | $1M | 0.5% | 2026-Q1 |
| Legato Capital Management LLC trimmed | 153,450 | $939K | 0.5% | 2026-Q1 |
| Russell Investments Group, Ltd. added | 145,329 | $889K | 0.5% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 144,547 | $885K | 0.5% | 2026-Q1 |
| MILLENNIUM MANAGEMENT LLC trimmed | 142,422 | $872K | 0.5% | 2026-Q1 |
| Mitsubishi UFJ Asset Management Co., Ltd. trimmed | 132,466 | $811K | 0.4% | 2026-Q1 |
| NANO CAP NEW MILLENNIUM GROWTH FUND L P | 120,000 | $734K | 0.4% | 2026-Q1 |
| DIMENSIONAL FUND ADVISORS LP trimmed | 118,751 | $726K | 0.4% | 2026-Q1 |
| GOLDMAN SACHS GROUP INC trimmed | 111,212 | $681K | 0.4% | 2026-Q1 |
| AQR CAPITAL MANAGEMENT LLC trimmed | 102,669 | $628K | 0.3% | 2026-Q1 |
| Nuveen, LLC added | 101,074 | $619K | 0.3% | 2026-Q1 |
| UBS Group AG trimmed | 93,445 | $572K | 0.3% | 2026-Q1 |
| IQ EQ FUND MANAGEMENT (IRELAND) Ltd added | 89,769 | $549K | 0.3% | 2026-Q1 |
| BANK OF MONTREAL /CAN/ trimmed | 87,375 | $535K | 0.3% | 2026-Q1 |
| Trexquant Investment LP added | 73,194 | $448K | 0.2% | 2026-Q1 |
| Cassaday & Co Wealth Management LLC | 71,629 | $438K | 0.2% | 2026-Q1 |
| Bruce & Co., Inc. | 68,286 | $418K | 0.2% | 2026-Q1 |
| LPL Financial LLC trimmed | 67,789 | $415K | 0.2% | 2026-Q1 |
| Bank of New York Mellon Corp trimmed | 59,041 | $361K | 0.2% | 2026-Q1 |
| AMERICAN CENTURY COMPANIES INC | 55,894 | $342K | 0.2% | 2026-Q1 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC | 50,500 | $309K | 0.2% | 2026-Q1 |
| Brooklyn Investment Group trimmed | 46,259 | $283K | 0.2% | 2026-Q1 |
| TWO SIGMA INVESTMENTS, LP trimmed | 44,127 | $270K | 0.1% | 2026-Q1 |
| XTX Topco Ltd added | 41,365 | $253K | 0.1% | 2026-Q1 |
| Old Port Advisors | 38,629 | $236K | 0.1% | 2026-Q1 |
| RHUMBLINE ADVISERS trimmed | 34,550 | $211K | 0.1% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 33,841 | $207K | 0.1% | 2026-Q1 |
| Campbell & CO Investment Adviser LLC trimmed | 29,656 | $181K | 0.1% | 2026-Q1 |
| ALLIANCEBERNSTEIN L.P. trimmed | 33,150 | $174K | 0.1% | 2026-Q1 |
| STATE OF WISCONSIN INVESTMENT BOARD trimmed | 26,198 | $160K | 0.1% | 2026-Q1 |
| BANK OF AMERICA CORP /DE/ trimmed | 25,078 | $153K | 0.1% | 2026-Q1 |
| Quantinno Capital Management LP added | 23,725 | $145K | 0.1% | 2026-Q1 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 19,385 | $119K | 0.1% | 2026-Q1 |
| DEUTSCHE BANK AG\ | 18,429 | $113K | 0.1% | 2026-Q1 |
| 49 WEALTH MANAGEMENT, LLC trimmed | 17,101 | $105K | 0.1% | 2026-Q1 |
| MetLife Investment Management, LLC added | 17,022 | $104K | 0.1% | 2026-Q1 |
| Cresset Asset Management, LLC trimmed | 16,343 | $100K | 0.1% | 2026-Q1 |
| JANE STREET GROUP, LLC trimmed | 14,301 | $88K | 0.0% | 2026-Q1 |
| Invesco Ltd. trimmed | 14,128 | $86K | 0.0% | 2026-Q1 |
| Dynamic Technology Lab Private Ltd trimmed | 13,898 | $85K | 0.0% | 2026-Q1 |
| Graham Capital Management, L.P. trimmed | 13,247 | $81K | 0.0% | 2026-Q1 |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. added | 13,028 | $80K | 0.0% | 2026-Q1 |
| Concurrent Investment Advisors, LLC added | 11,903 | $73K | 0.0% | 2026-Q1 |
| PCM Encore, LLC | 11,830 | $72K | 0.0% | 2026-Q1 |
| JPMORGAN CHASE & CO added | 11,300 | $65K | 0.0% | 2026-Q1 |
| FMR LLC trimmed | 10,543 | $65K | 0.0% | 2026-Q1 |
| WELLS FARGO & COMPANY/MN trimmed | 10,480 | $64K | 0.0% | 2026-Q1 |
| Vanguard Global Advisers, LLC new | 10,286 | $63K | 0.0% | 2026-Q1 |
| VANGUARD GROUP INC added | 1,470,864 | $8M | 4.1% | 2025-Q4 stale |
| MARSHALL WACE, LLP trimmed | 190,635 | $1M | 0.5% | 2025-Q4 stale |
| Schonfeld Strategic Advisors LLC trimmed | 103,025 | $902K | 0.5% | 2025-Q3 stale |
| Parkman Healthcare Partners LLC added | 100,368 | $879K | 0.5% | 2025-Q3 stale |
| HRT FINANCIAL LP added | 154,830 | $812K | 0.4% | 2025-Q4 stale |
| Informed Momentum Co LLC added | 86,595 | $759K | 0.4% | 2025-Q3 stale |
| Manatuck Hill Partners, LLC new | 80,000 | $570K | 0.3% | 2025-Q2 stale |
| ACADIAN ASSET MANAGEMENT LLC added | 81,862 | $428K | 0.2% | 2025-Q4 stale |
| Cubist Systematic Strategies, LLC added | 47,934 | $420K | 0.2% | 2025-Q3 stale |
| FourThought Financial Partners, LLC new | 37,334 | $327K | 0.2% | 2025-Q3 stale |
| Point72 Asset Management, L.P. added | 55,945 | $294K | 0.2% | 2025-Q4 stale |
| D. E. Shaw & Co., Inc. trimmed | 25,603 | $224K | 0.1% | 2025-Q3 stale |
| PDT Partners, LLC added | 41,600 | $186K | 0.1% | 2025-Q1 stale |
| ZACKS INVESTMENT MANAGEMENT added | 25,720 | $183K | 0.1% | 2025-Q2 stale |
| STRS OHIO added | 29,700 | $156K | 0.1% | 2025-Q4 stale |
| SG Americas Securities, LLC trimmed | 17,651 | $155K | 0.1% | 2025-Q3 stale |
| AXQ CAPITAL, LP added | 28,125 | $148K | 0.1% | 2025-Q4 stale |
| Engineers Gate Manager LP added | 26,681 | $140K | 0.1% | 2025-Q4 stale |
| OPAL CAPITAL LLC new | 17,581 | $121K | 0.1% | 2025-Q4 stale |
| Brevan Howard Capital Management LP new | 11,600 | $102K | 0.1% | 2025-Q3 stale |
| Thrivent Financial for Lutherans | 23,470 | $85K | 0.0% | 2025-Q1 stale |
| HSBC HOLDINGS PLC trimmed | 20,264 | $85K | 0.0% | 2025-Q1 stale |
| Walleye Capital LLC new | 11,504 | $82K | 0.0% | 2025-Q2 stale |
| Catalyst Funds Management Pty Ltd new | 11,400 | $81K | 0.0% | 2025-Q2 stale |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE added | 10,869 | $77K | 0.0% | 2025-Q2 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.