Rapid Micro Biosystems, Inc. (RPID) shareholders
RPIDNasdaqLaboratory Analytical InstrumentsFiscal year ends December 31
Financials through Q2 FY2026, quarter ended Jun 30, 2026Last filing: 10-Q on Aug 7, 2026Score 7/3057% below fair value
$0.65−0.02 (-2.98%)
Close on Nov 13, 2026Market cap $32.65MP/E –Yield –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
34.9%
18M of 50M shares
Institutional holders
34
5 new, 16 sold out
Net institutional buying
2M
In Q2 2026
Insider trades, 12 months
0 buys · 14 sales
Net sold $1.14M
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| Bain Capital Life Sciences Fund, L.P. | 7,651,369 | 16.76% | 13G (passive) amendment | Jun 30, 2026 |
| Longitude Capital Partners II, LLC Joint filing with Longitude Venture Partners II, L.P. (8.60%), Patrick G. Enright (8.60%) and 1 more | 3,529,245 | 8.60% | 13G (passive) amendment | Mar 31, 2026 |
| Steven Boyd Joint filing with Armistice Capital, LLC (7.29%) | 3,328,000 | 7.29% | 13G (passive) | Jun 30, 2026 |
| Spignesi Robert G Jr | 2,647,256 | 6.30% | 13D (active) | Mar 28, 2024 |
| Endeavour Medtech Growth II Parallel LP Joint filing with Endeavour Medtech Growth II LP (5.70%), Endeavour Medtech II GP Limited (5.70%) | 2,257,099 | 5.70% | 13G (passive) amendment | Dec 31, 2025 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of RPID | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| Bain Capital Life Sciences Investors, LLC | 8,434,560 | 16.82% | $14.59M | – | 0.87% |
| Armistice Capital, LLC | 3,328,000 | 6.63% | $5.76M | New | 0.07% |
| ABG-WTT Global Life Science Capital Partners GP Ltd | 1,848,296 | 3.68% | $3.20M | – | 37.39% |
| Vanguard Capital Management LLC | 982,034 | 1.96% | $1.70M | −460 | 0.00% |
| Evernest Financial Advisors, LLC | 506,000 | 1.01% | $875.38K | +73,490 | 0.18% |
| Advent International, L.P. | 379,794 | 0.76% | $657.04K | −172,583 | 0.00% |
| Essex Investment Management Co LLC | 362,696 | 0.72% | $627.46K | −521,235 | 0.08% |
| Millennium Management LLC | 236,599 | 0.47% | $409.32K | −46,681 | 0.00% |
| Geode Capital Management, LLC | 228,041 | 0.45% | $394.71K | −19,136 | 0.00% |
| Renaissance Technologies LLC | 212,101 | 0.42% | $366.94K | +85,484 | 0.00% |
| BlackRock, Inc. | 189,832 | 0.38% | $328.41K | +32,600 | 0.00% |
| Legato Capital Management LLC | 119,534 | 0.24% | $206.79K | −155,390 | 0.02% |
| Vanguard Fiduciary Trust Co | 110,484 | 0.22% | $191.14K | +772 | 0.00% |
| Dimensional Fund Advisors LP | 104,192 | 0.21% | $180.25K | +16,603 | 0.00% |
| State Street Corp | 93,874 | 0.19% | $162.40K | – | 0.00% |
| XTX Topco Ltd | 79,727 | 0.16% | $137.93K | +18,657 | 0.00% |
| Sei Investments Co | 66,869 | 0.13% | $115.68K | −217,947 | 0.00% |
| Northern Trust Corp | 42,106 | 0.08% | $72.84K | −6,173 | 0.00% |
| Algert Global LLC | 38,307 | 0.08% | $66.27K | +15,126 | 0.00% |
| Morgan Stanley | 27,587 | 0.05% | $47.73K | −1,620 | 0.00% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 34 | 18M | 34.9% | 5 / 9 | 13 / 16 | 4M | 2M |
| Q1 2026 | 46 | 16M | 31.6% | 13 / 17 | 9 / 8 | 3M | 1M |
| Q4 2025 | 42 | 15M | 29.1% | 15 / 11 | 8 / 2 | 1M | 1M |
| Q3 2025 | 29 | 15M | 29.6% | 4 / 9 | 7 / 4 | 0M | 1M |
| Q2 2025 | 29 | 15M | 30.2% | 3 / 11 | 8 / 2 | 0M | 0M |
| Q1 2025 | 28 | 15M | 30.5% | 13 / 8 | 4 / 4 | 4M | 0M |
| Q4 2024 | 19 | 12M | 23.8% | 2 / 6 | 3 / 1 | 0M | 1M |
| Q3 2024 | 19 | 18M | 35.6% | 3 / 2 | 6 / 4 | 1M | 1M |
| Q2 2024 | 21 | 19M | 38.0% | 1 / 5 | 7 / 3 | 0M | 1M |
| Q1 2024 | 23 | 20M | 39.3% | 1 / 6 | 7 / 4 | 0M | 1M |
| Q4 2023 | 26 | 21M | 41.6% | 5 / 7 | 4 / 2 | 0M | 1M |
| Q3 2023 | 23 | 21M | 42.8% | 1 / 4 | 8 / 2 | 0M | 0M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
20 funds held RPID in Q2 2026, 69% of their shares through ETFs. Each fund counts once per quarter, from its quarter-end report.
| Fund | Shares | % of RPID | Value | % of fund | As of |
|---|---|---|---|---|---|
| Vanguard Total Stock Market Index Fund | 750,984 | 1.50% | $1.30M | 0.00% | Jun 30, 2026 |
| Vanguard Extended Market Index Fund | 202,760 | 0.40% | $350.77K | 0.00% | Jun 30, 2026 |
| iShares Micro-Cap ETF | 112,127 | 0.22% | $193.98K | 0.01% | Jun 30, 2026 |
| Fidelity Extended Market Index Fund | 107,845 | 0.22% | $216.77K | 0.00% | May 31, 2026 |
| Fidelity Total Market Index Fund | 31,525 | 0.06% | $63.37K | 0.00% | May 31, 2026 |
| Dimensional U.S. Small Cap ETF | 30,705 | 0.06% | $65.40K | 0.00% | Jul 31, 2026 |
| Fidelity Series Total Market Index Fund | 28,726 | 0.06% | $57.74K | 0.00% | May 31, 2026 |
| Fidelity Nasdaq Composite Index Fund | 26,152 | 0.05% | $52.57K | 0.00% | May 31, 2026 |
| U.S. Micro Cap Portfolio | 14,363 | 0.03% | $30.59K | 0.00% | Jul 31, 2026 |
| Vanguard Balanced Index Fund | 14,205 | 0.03% | $24.57K | 0.00% | Jun 30, 2026 |
| Vanguard Institutional Total Stock Market Index Fund | 14,085 | 0.03% | $24.37K | 0.00% | Jun 30, 2026 |
| Avantis U.S. Small Cap Equity ETF | 11,638 | 0.02% | $23.39K | 0.00% | May 31, 2026 |
| 1290 VT Micro Cap Portfolio | 7,524 | 0.02% | $13.02K | 0.01% | Jun 30, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| Robert G. Spignesi Jr. | PRESIDENT AND CEO, Director | 1,191,973 | 2.38% | Jul 24, 2026 |
| Sean M. Wirtjes | CHIEF FINANCIAL OFFICER | 568,981 | 1.13% | Jun 2, 2026 |
| John J. Addington Wilson | CHIEF OPERATING OFFICER | 316,762 | 0.63% | Mar 12, 2026 |
| Richard S. Kollender | Director | 1,613,008 | 3.22% | Jul 24, 2026 |
| Inese Lowenstein | Director | 70,687 | 0.14% | Jun 2, 2026 |
| Kirk Malloy | Director | 70,687 | 0.14% | Jun 2, 2026 |
| Melinda Litherland Pei | Director | 100,687 | 0.20% | Jun 2, 2026 |
| Dafni Bika | Director | 19,300 | 0.04% | May 26, 2026 |
| Natale S. Ricciardi | Director | 29,442 | 0.06% | Mar 2, 2026 |
| Bain Capital Life Sciences Partners, LP | 10% owner | – | – | May 22, 2026 |
| BCIP Life Sciences Associates, LP | 10% owner | – | – | May 22, 2026 |
| Bain Capital Life Sciences Fund, L.P. | 10% owner | 8,434,560 | 16.82% | May 22, 2026 |
| Bain Capital Life Sciences Investors, LLC | 10% owner | 6,999,998 | 13.96% | May 22, 2026 |
| Longitude Capital Partners II, LLC | 10% owner | – | – | Feb 6, 2026 |
| Patrick G. Enright | 10% owner | 63,914 | 0.13% | Feb 6, 2026 |
| Longitude Prime Partners, LLC | 10% owner | 49,000 | 0.10% | Feb 6, 2026 |
| Longitude Prime Fund, L.P. | 10% owner | – | – | Feb 6, 2026 |
| Longitude Venture Partners II, L.P. | 10% owner | 4,029,245 | 8.03% | Feb 6, 2026 |
| Bakker Juliet Tammenoms | 10% owner | – | – | Feb 6, 2026 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Richard S. Kollender Director | Jul 24, 2026 | Option exercise | +1,681 | $0.75 | $1.26K | 131,999 |
| Richard S. Kollender Director | Jul 24, 2026 | Option exercise | +1,827 | $0.75 | $1.37K | 133,826 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 22, 2026 | Option exercise | +1,402 | $0.75 | $1.05K | 1,191,973 |
| Melinda Litherland Pei Director | May 29, 2026 | Award | +12,787 | $1.96 | $25.06K | 100,687 |
| Inese Lowenstein Director | May 29, 2026 | Award | +12,787 | $1.96 | $25.06K | 70,687 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | May 29, 2026 | Award | +12,787 | $1.96 | $25.06K | 1,190,571 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | May 29, 2026 | Award | +12,787 | $1.96 | $25.06K | 568,981 |
| Kirk Malloy Director | May 29, 2026 | Award | +12,787 | $1.96 | $25.06K | 60,687 |
| Inese Lowenstein Director | May 21, 2026 | Award | +19,300 | – | – | 57,900 |
| Kirk Malloy Director | May 21, 2026 | Award | +19,300 | – | – | 47,900 |
| Richard S. Kollender Director | May 21, 2026 | Award | +19,300 | – | – | 130,318 |
| Melinda Litherland Pei Director | May 21, 2026 | Award | +19,300 | – | – | 87,900 |
| Dafni Bika Director | May 21, 2026 | Award | +19,300 | – | – | 19,300 |
| John J. Addington Wilson CHIEF OPERATING OFFICER | Mar 11, 2026 | Sale | −9,603 | $4.32 | $41.48K | 316,762 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Mar 11, 2026 | Sale | −7,480 | $4.32 | $32.31K | 556,194 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Mar 10, 2026 | Sale | −17,922 | $4.11 | $73.66K | 1,169,848 |
| Natale S. Ricciardi Director | Feb 27, 2026 | Option exercise | +842 | $0.75 | $632 | 29,442 |
| John J. Addington Wilson CHIEF OPERATING OFFICER | Feb 20, 2026 | Sale | −5,403 | $3.92 | $21.18K | 326,365 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Feb 20, 2026 | Sale | −17,254 | $3.92 | $67.64K | 563,674 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Feb 19, 2026 | Sale | −38,327 | $3.89 | $149.09K | 1,187,770 |
| John J. Addington Wilson CHIEF OPERATING OFFICER | Feb 11, 2026 | Award | +74,000 | – | – | 331,768 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Feb 11, 2026 | Award | +264,000 | – | – | 1,226,097 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Feb 11, 2026 | Award | +97,000 | – | – | 580,928 |
| John J. Addington Wilson CHIEF OPERATING OFFICER | Feb 9, 2026 | Sale | −4,610 | $3.78 | $17.43K | 257,768 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Feb 9, 2026 | Sale | −12,840 | $3.78 | $48.54K | 962,097 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Feb 9, 2026 | Sale | −6,027 | $3.78 | $22.78K | 483,928 |
| Longitude Venture Partners II, L.P. 10% owner | Feb 4, 2026 | Sale | −49,000 | $3.88 | $190.12K | 0 |
| Longitude Prime Partners, LLC 10% owner | Feb 3, 2026 | Sale | −27,500 | $4.24 | $116.60K | 49,000 |
| Longitude Prime Partners, LLC 10% owner | Feb 2, 2026 | Sale | −27,500 | $4.25 | $116.88K | 76,500 |
| Longitude Prime Partners, LLC 10% owner | Jan 30, 2026 | Sale | −46,000 | $4.54 | $208.84K | 104,000 |
| Longitude Prime Partners, LLC 10% owner | Jan 23, 2026 | Sale | −7,739 | $4.06 | $31.42K | 4,029,245 |
| Longitude Prime Partners, LLC 10% owner | Jan 23, 2026 | Option exercise | +629,032 | $0.05 | $31.45K | 4,036,984 |
| Kirk Malloy Director | Nov 14, 2025 | Gift | −40,000 | – | – | 28,600 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Oct 17, 2025 | Option exercise | +3,400 | $0.75 | $2.55K | 973,950 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Oct 17, 2025 | Tax withholding | −2,072 | $3.08 | $6.38K | 971,878 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Oct 17, 2025 | Option exercise | +7,833 | $0.75 | $5.87K | 979,711 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Oct 17, 2025 | Tax withholding | −4,774 | $3.08 | $14.70K | 974,937 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 14, 2025 | Sale | −11,881 | $3.32 | $39.44K | 970,550 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 14, 2025 | Option exercise | +25,145 | – | – | 982,431 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 11, 2025 | Sale | −11,874 | $3.33 | $39.54K | 957,286 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 11, 2025 | Option exercise | +25,145 | – | – | 969,160 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 10, 2025 | Sale | −11,617 | $3.40 | $39.50K | 944,015 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 10, 2025 | Option exercise | +25,145 | – | – | 925,728 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 9, 2025 | Option exercise | +25,144 | – | – | 911,830 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 9, 2025 | Sale | −11,247 | $3.51 | $39.48K | 900,583 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 8, 2025 | Option exercise | +25,144 | – | – | 897,510 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Jul 8, 2025 | Sale | −10,824 | $3.51 | $37.99K | 886,686 |
| Kirk Malloy Director | May 22, 2025 | Award | +14,300 | – | – | 78,600 |
| Inese Lowenstein Director | May 22, 2025 | Award | +14,300 | – | – | 38,600 |
| Richard S. Kollender Director | May 22, 2025 | Award | +14,300 | – | – | 111,018 |
| Melinda Litherland Pei Director | May 22, 2025 | Award | +14,300 | – | – | 68,600 |
| Natale S. Ricciardi Director | May 22, 2025 | Award | +14,300 | – | – | 28,600 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Mar 9, 2025 | Tax withholding | −10,650 | $2.39 | $25.45K | 872,366 |
| John J. Addington Wilson CHIEF OPERATING OFFICER | Mar 9, 2025 | Tax withholding | −9,872 | $2.39 | $23.59K | 232,474 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Mar 9, 2025 | Tax withholding | −7,690 | $2.39 | $18.38K | 489,955 |
| John J. Addington Wilson CHIEF OPERATING OFFICER | Feb 18, 2025 | Award | +44,000 | – | – | 242,346 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Feb 18, 2025 | Award | +365,000 | – | – | 883,016 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Feb 18, 2025 | Award | +160,000 | – | – | 497,645 |
| Sean M. Wirtjes CHIEF FINANCIAL OFFICER | Feb 11, 2025 | Tax withholding | −4,621 | $2.68 | $12.38K | 337,645 |
| Robert G. Spignesi Jr. PRESIDENT AND CEO, Director | Feb 11, 2025 | Tax withholding | −10,755 | $2.68 | $28.82K | 516,205 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Short interest
Shares sold short and not yet bought back, as of Oct 30, 2026 (FINRA, reported twice a month)
Short % of float
2.93%
1M shares short
Days to cover
5.5
At 0M shares a day
Change since last report
-12.7%
From 1M shares
Short volume, 20 days
53.7%
Of volume reported to FINRA
Shares sold short, last 12 months
Short sale volume counts trades marked short on any given day, including market-maker hedging, so it runs far higher than the share of Rapid Micro Biosystems's stock actually held short. Settlement fails (shares not delivered on time) peaked at 61,313 shares on Aug 18, 2026 over the last 90 days.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| John J. Addington Wilson Former Officer | Jul 8, 2026 | 10,000 | $17.04K | Jul 8, 2026 | Stock Option Exercise |
| John J. Addington Wilson Former Officer | Jul 1, 2026 | 6,312 | $11.05K | Jul 1, 2026 | Stock Option Exercise |
| John J. Addington Wilson Former Officer | Jun 22, 2026 | 3,688 | $6.45K | Jun 22, 2026 | Stock Option Exercise |
| John J. Addington Wilson Former Officer | Jun 10, 2026 | 5,000 | $9.35K | Jun 10, 2026 | Stock Option Exercise |
| Sean M. Wirtjes Officer | Mar 11, 2026 | 7,480 | $32.30K | Mar 11, 2026 | Restricted Stock Vesting |
| John J. Addington Wilson Officer | Mar 11, 2026 | 9,603 | $41.47K | Mar 11, 2026 | Restricted Stock Vesting |
| Robert G. Spignesi Jr. Officer, Director | Mar 10, 2026 | 17,922 | $73.69K | Mar 10, 2026 | Restricted Stock Vesting |
| John J. Addington Wilson Officer | Feb 20, 2026 | 5,403 | $21.20K | Feb 20, 2026 | Restricted Stock Vesting |
| Sean M. Wirtjes Officer | Feb 20, 2026 | 17,254 | $67.69K | Feb 20, 2026 | Restricted Stock Vesting |
| Robert G. Spignesi Jr. Officer, Director | Feb 19, 2026 | 38,327 | $148.91K | Feb 19, 2026 | Restricted Stock Vesting |
| Robert G. Spignesi Jr. Officer, Director | Feb 9, 2026 | 12,840 | $48.57K | Feb 9, 2026 | Restricted Stock Vesting |
| John J. Addington Wilson Officer | Feb 9, 2026 | 4,610 | $17.44K | Feb 9, 2026 | Restricted Stock Vesting |
| Sean M. Wirtjes Officer | Feb 9, 2026 | 6,027 | $22.80K | Feb 9, 2026 | Restricted Stock Vesting |
| Robert G. Spignesi Jr. Officer, Director | Jul 14, 2025 | 11,881 | $39.48K | Jul 14, 2025 | Restricted Stock Vesting |
| Robert G. Spignesi Jr. Officer, Director | Jul 11, 2025 | 11,874 | $39.50K | Jul 11, 2025 | Restricted Stock Vesting |
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