Rapid Micro Biosystems, Inc. (RPID) Ownership
RPID ownership summary
as of October 18, 2026- Institutions
- 46.2% of shares outstanding
- Insiders
- 10.11% of shares outstanding
- Shares outstanding
- 45.7M
- Float
- 23.9M shares available to trade
- Short interest
- 2.76% 854K shares short
- Days to cover
- 2.70 short interest down 9.2% vs prior month
- Institutions 46.21%
- Insiders 10.11%
- Other investors 43.69%
RPID top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Bain Capital Life Sciences Investors, LLC | 16.82% | 8.4M | $6.4M | — | June 30, 2026 |
| 2 | Armistice Capital, LLC | 6.63% | 3.3M | $2.5M | +3.3M (0.0%) | June 30, 2026 |
| 3 | ABG-WTT Global Life Science Capital Partners GP Ltd | 3.68% | 1.8M | $1.4M | — | June 30, 2026 |
| 4 | Vanguard Capital Management, LLC | 1.96% | 982K | $750,274 | −460 (−0.0%) | June 30, 2026 |
| 5 | Evernest Financial Advisors LLC | 1.01% | 506K | $386,584 | +73,490 (+17.0%) | June 30, 2026 |
| 6 | Advent International LP | 0.76% | 380K | $290,163 | −172,583 (−31.2%) | June 30, 2026 |
| 7 | Essex Investment Management Company, LLC | 0.72% | 363K | $277,100 | −521,235 (−59.0%) | June 30, 2026 |
| 8 | Millennium Management LLC | 0.47% | 237K | $180,762 | −46,681 (−16.5%) | June 30, 2026 |
| 9 | Geode Capital Management, LLC | 0.45% | 228K | $174,223 | −19,136 (−7.7%) | June 30, 2026 |
| 10 | Renaissance Technologies Corp | 0.42% | 212K | $162,045 | +85,484 (+67.5%) | June 30, 2026 |
| 11 | BlackRock Inc | 0.38% | 190K | $145,032 | +32,600 (+20.7%) | June 30, 2026 |
| 12 | 683 Capital Management LLC | 0.24% | 121K | $92,271 | — | March 31, 2026 |
| 13 | Legato Capital Management LLC | 0.24% | 120K | $91,324 | −155,390 (−56.5%) | June 30, 2026 |
| 14 | Vanguard Fiduciary Trust Co | 0.22% | 110K | $84,410 | +772 (+0.7%) | June 30, 2026 |
| 15 | Dimensional Fund Advisors, Inc. | 0.21% | 104K | $79,603 | +16,603 (+19.0%) | June 30, 2026 |
| 16 | State Street Corp | 0.19% | 94K | $71,720 | — | June 30, 2026 |
| 17 | XTX Topco Ltd | 0.16% | 80K | $60,911 | +18,657 (+30.6%) | June 30, 2026 |
| 18 | SEI Investments Co | 0.13% | 67K | $51,088 | −217,947 (−76.5%) | June 30, 2026 |
| 19 | Northern Trust Corp | 0.08% | 42K | $32,169 | −6,173 (−12.8%) | June 30, 2026 |
| 20 | Algert Global LLC | 0.08% | 38K | $29,267 | +15,126 (+65.3%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 8 holders added 3.6M shares and 8 cut 1.1M.
RPID top mutual fund and ETF holders
18 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 1.50% | 751K | $573,752 | — | August 31, 2026 |
| 2 | iShares Micro-Cap ETF | 0.24% | 119K | $91,060 | −822 (−0.7%) | September 30, 2026 |
| 3 | Fidelity Extended Market Index | 0.22% | 112K | $85,444 | +8,454 (+8.2%) | August 31, 2026 |
| 4 | Fidelity Total Market Index | 0.06% | 32K | $24,085 | — | August 31, 2026 |
| 5 | Fidelity Nasdaq Composite Index | 0.06% | 29K | $22,531 | — | August 31, 2026 |
| 6 | Fidelity Series Total Market Index | 0.06% | 29K | $21,947 | — | August 31, 2026 |
| 7 | DFA US Micro Cap I | 0.03% | 14K | $10,973 | — | August 31, 2026 |
| 8 | Avantis US Small Cap Equity ETF | 0.02% | 12K | $8,891 | — | September 30, 2026 |
| 9 | Vanguard U.S. Eq Idx £ Acc | 0.02% | 12K | $8,885 | — | August 31, 2026 |
| 10 | Dimensional US Small Cap ETF | 0.02% | 12K | $8,838 | — | September 30, 2026 |
| 11 | Vanguard Balanced Index Inv | 0.02% | 10K | $7,692 | −4,137 (−29.1%) | August 31, 2026 |
| 12 | Dimensional Global Core Equity USD Acc | 0.02% | 8,671 | $6,625 | — | August 31, 2026 |
| 13 | 1290 VT Micro Cap K | 0.01% | 7,524 | $5,748 | — | August 31, 2026 |
| 14 | Dimensional World Equity GBP Acc | 0.01% | 4,141 | $3,164 | — | August 31, 2026 |
| 15 | Dimensional Gl Cor Eq LC ESG Sc USD A | 0.01% | 3,097 | $2,366 | — | August 31, 2026 |
| 16 | Dimensional US Core Equity USD Acc | 0.01% | 3,009 | $2,299 | — | August 31, 2026 |
| 17 | Dimensional International Core Eq Acc | 0.01% | 2,975 | $2,273 | — | August 31, 2026 |
| 18 | Dimensional Global Small Coms USD Acc | <0.01% | 2,089 | $1,596 | — | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
RPID insider transactions
latest 18| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2026-03-11 | Sean M Wirtjes | Sell | $4.32 | 7,480 | $32,314 |
| 2026-03-11 | John J Addington Wilson | Sell | $4.32 | 9,603 | $41,485 |
| 2026-03-10 | Robert G Jr. Spignesi | Sell | $4.11 | 17,922 | $73,659 |
| 2026-02-20 | John J Addington Wilson | Sell | $3.92 | 5,403 | $21,180 |
| 2026-02-20 | Sean M Wirtjes | Sell | $3.92 | 17,254 | $67,636 |
| 2026-02-19 | Robert G Jr. Spignesi | Sell | $3.89 | 38,327 | $149,092 |
| 2026-02-09 | John J Addington Wilson | Sell | $3.78 | 4,610 | $17,426 |
| 2026-02-09 | Robert G Jr. Spignesi | Sell | $3.78 | 12,840 | $48,535 |
| 2026-02-09 | Sean M Wirtjes | Sell | $3.78 | 6,027 | $22,782 |
| 2026-02-04 | Longitude Capital Partners Ii, | Sell | $3.88 | 49,000 | $190,120 |
| 2026-02-02 | Longitude Capital Partners Ii, | Sell | $4.25 | 27,500 | $116,875 |
| 2026-01-30 | Longitude Capital Partners Ii, | Sell | $4.54 | 46,000 | $208,840 |
| 2026-01-23 | Longitude Capital Partners Ii, | Sell | $4.06 | 7,739 | $31,420 |
| 2025-07-14 | Robert G Jr. Spignesi | Sell | $3.32 | 11,881 | $39,445 |
| 2025-07-11 | Robert G Jr. Spignesi | Sell | $3.33 | 11,874 | $39,540 |
| 2025-07-10 | Robert G Jr. Spignesi | Sell | $3.40 | 11,617 | $39,498 |
| 2025-07-09 | Robert G Jr. Spignesi | Sell | $3.51 | 11,247 | $39,477 |
| 2025-07-08 | Robert G Jr. Spignesi | Sell | $3.51 | 10,824 | $37,992 |
Reported trades by company officers, directors and other filers (including disclosures by members of Congress where EODHD lists them). "—" where the filing gives no share count.
RPID shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns RPID
Institutional investors own 46.2% of Rapid Micro Biosystems's shares and insiders 10.11%. The largest holder is Bain Capital Life Sciences Investors, LLC with 16.82% of the shares (8.4M), as of June 30, 2026. Among the top 20 institutions, 8 added shares and 8 reduced their stake in the latest filings. Short interest is 2.76% of the float, or 2.70 days of average trading volume. The share count rose 40.6% since 2019.
Related: RPID analyst forecast, RPID key metrics. See the RPID stock overview for the latest quote and news.
RPID ownership FAQ
Who owns the most Rapid Micro Biosystems stock?
The largest shareholders of Rapid Micro Biosystems are Bain Capital Life Sciences Investors, LLC (16.82%), Armistice Capital, LLC (6.63%), ABG-WTT Global Life Science Capital Partners GP Ltd (3.68%), Vanguard Capital Management, LLC (1.96%), Evernest Financial Advisors LLC (1.01%).
What percentage of Rapid Micro Biosystems is owned by institutions?
Institutions hold 46.2% of Rapid Micro Biosystems's shares outstanding; insiders hold 10.11%.
Which funds own Rapid Micro Biosystems?
The largest fund holders of Rapid Micro Biosystems are Vanguard MStar Total Stk Mkt Idx Invest (1.50%), iShares Micro-Cap ETF (0.24%), Fidelity Extended Market Index (0.22%), Fidelity Total Market Index (0.06%), Fidelity Nasdaq Composite Index (0.06%).
What is Rapid Micro Biosystems's short interest?
854K shares of Rapid Micro Biosystems were sold short, 2.76% of the float; at the average daily volume it would take 2.70 days to cover.
Are insiders buying or selling Rapid Micro Biosystems?
Of the latest 18 reported insider transactions in Rapid Micro Biosystems (since July 8, 2025), 0 were purchases and 18 were sales.
How many shares of Rapid Micro Biosystems are outstanding?
Rapid Micro Biosystems has 45.7M shares outstanding, of which 23.9M are in the public float.