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CTKB SCHEDULE 13G/A: SEC filing

Boston Partners

Filed with the SEC on · accession 0001386060-26-000063

CTKB filed a SCHEDULE 13G/A (schedule 13g/a) with the SEC on Nov 13, 2026. Boston Partners filed an amended Schedule 13G/A disclosing beneficial ownership of 8,002,638 shares, or 6.16%, of Cytek Biosciences common stock as of September 30, 2026. The stock moved +5.8% by the first close after the filing.

Summary of the filing

Boston Partners filed an amended Schedule 13G/A disclosing beneficial ownership of 8,002,638 shares, or 6.16%, of Cytek Biosciences common stock as of September 30, 2026. The filing is a passive institutional ownership update.

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Key details

Shares beneficially owned by Boston Partners$8.0M
Shares with sole voting power$6.5M
Reporting beneficial owner / institutional investorBoston Partners
Issuer of the securitiesCytek Biosciences, Inc.
Senior compliance manager, boston partnersAli Farooqi

How CTKB stock reacted

Close before

$5.52

Nov 12, 2026

First close after

+5.80%

$5.84

5 trading days

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Since filing

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Frequently asked questions

What did CTKB file with the SEC on Nov 13, 2026?

CTKB filed a SCHEDULE 13G/A (SEC filing). Boston Partners filed an amended Schedule 13G/A disclosing beneficial ownership of 8,002,638 shares, or 6.16%, of Cytek Biosciences common stock as of September 30, 2026. The filing is a passive institutional ownership update.

How do I read a SCHEDULE 13G/A?

A report the company filed with the SEC (the US market regulator). Start with the summary, then the key amounts and names. Compare it with the company’s earlier filings.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A SCHEDULE 13G/A (schedule 13g/a): A report the company filed with the SEC (the US market regulator).

How did CTKB stock react to this filing?

CTKB closed at $5.52 before the filing and $5.84 on Nov 13, 2026 (+5.80%).

Other CTKB SEC filings

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