SEPTInvestingStart Free

KPTI SCHEDULE 13G/A: SEC filing

Filed with the SEC on · accession 0001831942-26-000037

KPTI filed a SCHEDULE 13G/A (schedule 13g/a) with the SEC on Aug 14, 2026. Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz filed a joint filing agreement as part of an amended Schedule 13G for their position in Karyopharm Therapeutics Inc. The filing is a procedural joint filing agreement and does not disclose a change in… The stock moved +1.5% by the first close after the filing.

Summary of the filing

Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz filed a joint filing agreement as part of an amended Schedule 13G for their position in Karyopharm Therapeutics Inc. The filing is a procedural joint filing agreement and does not disclose a change in ownership stake.

For details, click here →

Key details

Filer/reporting personCommodore Capital LP
Filer/reporting personCommodore Capital Master LP
Subject companyKaryopharm Therapeutics Inc.
Managing partner, commodore capital lpMichael Kramarz
Reporting personRobert Egen Atkinson

How KPTI stock reacted

Close before

$1.99

Aug 13, 2026

First close after

+1.51%

$2.02

5 trading days

-8.54%

$1.82

Since filing

-97.24%

$0.05

✦ Ask GOAX AI about this filing — what it means for KPTI, what changed since its last filings and what to watch next.

Try it free for 7 days

🔔 Want to stay updated on new SEC filings for KPTI?

Click here

Frequently asked questions

What did KPTI file with the SEC on Aug 14, 2026?

KPTI filed a SCHEDULE 13G/A (SEC filing). Commodore Capital LP, Commodore Capital Master LP, Robert Egen Atkinson, and Michael Kramarz filed a joint filing agreement as part of an amended Schedule 13G for their position in Karyopharm Therapeutics Inc. The filing is a procedural joint filing agreement and does not disclose a change in ownership stake.

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 KPTI stock react to this filing?

KPTI closed at $1.99 before the filing and $2.02 on Aug 14, 2026 (+1.51%). Five trading days later: $1.82 (-8.54%).

Other KPTI SEC filings

Get alerts when KPTI files with the SEC, plus live charts, key levels and news for 13,000+ stocks.

Try SEPT free for 7 days
KPTI overviewKPTI analysisKPTI newsLatest SEC filings