Atrium Therapeutics, Inc (RNA) grew to 1.91% of Paul Isaac's Arbiter Partners Capital Management portfolio in 2026 Q2, from 2.09%, according to the 13F-HR/A filed with the SEC on September 15, 2026. The share count rose 127% to 523K shares, and the position is worth about $7M and ranks 13th of 42 stocks by weight.
What did the 2026 Q2 filing report for RNA?
As of June 30, 2026, from the 13F-HR/A filed September 15, 2026.
| Before | After | |
|---|---|---|
| Shares | 230K | 523K |
| Shares added | +293K (127%) | |
| Reported value | $3.1M | $7M |
| Portfolio weight | 2.09% | 1.91% |
| Rank in portfolio | 13th of 42 |
How much did Paul Isaac add to RNA?
Paul Isaac added 293K shares of RNA during 2026 Q2, taking the stake from 230K to 523K. The reported value of the position rose by about $4M, from about $3.1M to about $7M.
Where does RNA sit in the Paul Isaac portfolio?
RNA ranks 13th of 42 stock positions in the Paul Isaac portfolio at 1.91%, about the fund's average stock position of 2%. The largest stock position is GRAL at 38.42%. Next come GEF-B at 9.86% and CRBG at 6.19%. The three largest stocks together are 54.47% of the book. The RNA addition was the 15th largest of the quarter's 45 position changes by percent change to portfolio. Across the 2026 Q2 portfolio, Paul Isaac reported 42 stock positions, with 5 opened and 3 closed. The total portfolio value is about $367.5M, up 149% from the prior quarter.
How long has Paul Isaac held RNA?
Paul Isaac first reported RNA in the quarter ended March 31, 2026. Every reported trade is on the Paul Isaac RNA trade history page.
FAQ
How many RNA shares did Paul Isaac buy in 2026 Q2?
Paul Isaac added 293K shares of RNA, a 127% increase, to 523K shares.
What is the RNA position of Paul Isaac worth now?
The RNA position of Paul Isaac is worth about $7M at June 30, 2026 prices, 1.91% of the portfolio.
Is RNA a top holding of Paul Isaac?
RNA ranks 13th of 42 stock positions in the Paul Isaac portfolio, at 1.91%.