Cytek Biosciences, Inc. (CTKB) Ownership
CTKB ownership summary
as of October 18, 2026- Institutions
- 62.8% of shares outstanding
- Insiders
- 8.47% of shares outstanding
- Shares outstanding
- 130.0M
- Float
- 102.9M shares available to trade
- Short interest
- 5.08% 5.2M shares short
- Days to cover
- 4.00 short interest down 0.5% vs prior month
- Institutions 62.82%
- Insiders 8.47%
- Other investors 28.71%
CTKB top institutional holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | BlackRock Inc | 7.37% | 9.6M | $50.3M | −7.4M (−43.7%) | June 30, 2026 |
| 2 | Millennium Management LLC | 7.18% | 9.3M | $49.0M | +3.0M (+48.4%) | June 30, 2026 |
| 3 | Boston Partners Global Investors, Inc | 5.89% | 7.7M | $40.2M | +1.9M (+32.0%) | June 30, 2026 |
| 4 | Hillhouse Capital Advisors, Ltd. | 5.12% | 6.7M | $34.9M | — | June 30, 2026 |
| 5 | Topline Capital Management LLC | 4.83% | 6.3M | $33.0M | −781,031 (−11.1%) | June 30, 2026 |
| 6 | Vanguard Capital Management, LLC | 3.80% | 4.9M | $25.9M | +176,693 (+3.7%) | June 30, 2026 |
| 7 | Geode Capital Management, LLC | 2.35% | 3.1M | $16.1M | +225,618 (+8.0%) | June 30, 2026 |
| 8 | Dimensional Fund Advisors, Inc. | 2.01% | 2.6M | $13.7M | −47,072 (−1.8%) | June 30, 2026 |
| 9 | State Street Corp | 1.97% | 2.6M | $13.5M | −1.6M (−37.8%) | June 30, 2026 |
| 10 | The Goldman Sachs Group Inc | 1.67% | 2.2M | $11.4M | −177,220 (−7.6%) | June 30, 2026 |
| 11 | Royce & Associates, LP | 1.60% | 2.1M | $10.9M | +439,211 (+26.7%) | June 30, 2026 |
| 12 | Acadian Asset Management LLC | 1.06% | 1.4M | $7.2M | +977,060 (+244.9%) | June 30, 2026 |
| 13 | Bank of America Corp | 1.01% | 1.3M | $6.9M | +306,278 (+30.4%) | June 30, 2026 |
| 14 | Vanguard Portfolio Management, LLC | 0.88% | 1.1M | $6.0M | −1.2M (−50.6%) | June 30, 2026 |
| 15 | Charles Schwab Investment Management Inc | 0.83% | 1.1M | $5.6M | −31,348 (−2.8%) | June 30, 2026 |
| 16 | Northern Trust Corp | 0.77% | 1.0M | $5.3M | −1,899 (−0.2%) | June 30, 2026 |
| 17 | HRT FINANCIAL LLC | 0.77% | 998K | $5.2M | +583,717 (+141.0%) | June 30, 2026 |
| 18 | Arrowstreet Capital Limited Partnership | 0.75% | 974K | $5.1M | +653,924 (+204.4%) | June 30, 2026 |
| 19 | Jane Street Group LLC | 0.70% | 906K | $4.8M | +906,162 (0.0%) | June 30, 2026 |
| 20 | Tudor Investment Corp Et AL | 0.64% | 838K | $4.4M | +517,198 (+161.3%) | June 30, 2026 |
Value at the latest close. Change = shares bought or sold in the latest quarterly filing (13F). In the top 20, 11 holders added 9.7M shares and 8 cut 11.2M.
CTKB top mutual fund and ETF holders
20 largest| # | Holder | % of shares | Shares | Value | Change | Reported |
|---|---|---|---|---|---|---|
| 1 | Vanguard MStar Total Stk Mkt Idx Invest | 2.71% | 3.5M | $18.5M | — | August 31, 2026 |
| 2 | iShares Russell 2000 ETF | 2.45% | 3.2M | $16.7M | −36,672 (−1.1%) | September 30, 2026 |
| 3 | Column Small Cap Select | 2.01% | 2.6M | $13.7M | +589,084 (+29.2%) | June 30, 2026 |
| 4 | Fidelity Small Cap Index | 1.02% | 1.3M | $7.0M | +11,979 (+0.9%) | July 31, 2026 |
| 5 | Royce Micro-Cap Trust | 1.02% | 1.3M | $6.9M | +321,061 (+32.1%) | June 30, 2026 |
| 6 | iShares Russell 2000 Value ETF | 0.88% | 1.1M | $6.0M | +1,738 (+0.2%) | September 30, 2026 |
| 7 | WPG Partners Select Small Cap Value Ins | 0.82% | 1.1M | $5.6M | +29,936 (+2.9%) | July 31, 2026 |
| 8 | iShares Biotechnology ETF | 0.73% | 944K | $5.0M | −7,152 (−0.8%) | September 30, 2026 |
| 9 | Vanguard Russell 2000 ETF | 0.54% | 698K | $3.7M | +13,884 (+2.0%) | August 31, 2026 |
| 10 | Goldman Sachs Small Cp Val Insghts Instl | 0.49% | 639K | $3.4M | +162,172 (+34.0%) | July 31, 2026 |
| 11 | Schwab US Small-Cap ETF™ | 0.46% | 600K | $3.1M | +405 (+0.1%) | September 30, 2026 |
| 12 | Fidelity Enhanced Small Cap Core ETF | 0.45% | 589K | $3.1M | +1,233 (+0.2%) | September 30, 2026 |
| 13 | Royce Micro-Cap Invmt | 0.44% | 572K | $3.0M | +94,796 (+19.8%) | June 30, 2026 |
| 14 | DFA US Small Cap I | 0.44% | 567K | $3.0M | — | August 31, 2026 |
| 15 | Dimensional US Core Equity 2 ETF | 0.29% | 373K | $2.0M | — | September 30, 2026 |
| 16 | DFA US Micro Cap I | 0.26% | 343K | $1.8M | — | August 31, 2026 |
| 17 | Vanguard Health Care ETF | 0.26% | 340K | $1.8M | +12,275 (+3.7%) | August 31, 2026 |
| 18 | Fidelity Extended Market Index | 0.24% | 314K | $1.6M | −1,687 (−0.5%) | August 31, 2026 |
| 19 | Russell Inv US Small Cap Equity Y | 0.24% | 313K | $1.6M | — | August 31, 2026 |
| 20 | Schwab Small Cap Index | 0.23% | 296K | $1.6M | — | August 31, 2026 |
Funds report holdings monthly or quarterly; dates differ by fund.
CTKB insider transactions
latest 2| Date | Name | Transaction | Price | Shares | Value |
|---|---|---|---|---|---|
| 2025-06-02 | William D Mccombe | Buy | $2.78 | 35,000 | $97,300 |
| 2025-06-02 | William D Mccombe | Buy | $2.78 | 35,000 | $97,300 |
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.
CTKB shares outstanding
Year-end shares outstanding, adjusted for splits.
Who owns CTKB
Institutional investors own 62.8% of Cytek Biosciences's shares and insiders 8.47%. The largest holder is BlackRock Inc with 7.37% of the shares (9.6M), as of June 30, 2026. Among the top 20 institutions, 11 added shares and 8 reduced their stake in the latest filings. Short interest is 5.08% of the float, or 4.00 days of average trading volume. The share count rose 4.2% since 2020.
Related: CTKB analyst forecast, CTKB key metrics. See the CTKB stock overview for the latest quote and news.
CTKB ownership FAQ
Who owns the most Cytek Biosciences stock?
The largest shareholders of Cytek Biosciences are BlackRock Inc (7.37%), Millennium Management LLC (7.18%), Boston Partners Global Investors, Inc (5.89%), Hillhouse Capital Advisors, Ltd. (5.12%), Topline Capital Management LLC (4.83%).
What percentage of Cytek Biosciences is owned by institutions?
Institutions hold 62.8% of Cytek Biosciences's shares outstanding; insiders hold 8.47%.
Which funds own Cytek Biosciences?
The largest fund holders of Cytek Biosciences are Vanguard MStar Total Stk Mkt Idx Invest (2.71%), iShares Russell 2000 ETF (2.45%), Column Small Cap Select (2.01%), Fidelity Small Cap Index (1.02%), Royce Micro-Cap Trust (1.02%).
What is Cytek Biosciences's short interest?
5.2M shares of Cytek Biosciences were sold short, 5.08% of the float; at the average daily volume it would take 4.00 days to cover.
Are insiders buying or selling Cytek Biosciences?
Of the latest 2 reported insider transactions in Cytek Biosciences (since June 2, 2025), 2 were purchases and 0 were sales.
How many shares of Cytek Biosciences are outstanding?
Cytek Biosciences has 130.0M shares outstanding, of which 102.9M are in the public float.