Atrium Therapeutics RNA
-23.1%vs Day 1Spinoff of Avidity Bio (RNA) · Pre-Acquisition Spin · Spun Feb 26, 2026
Current Stats
Post-Spinoff Performance
| Timeline | |
| Spinoff date | February 26, 2026 · Nasdaq |
| Days since spinoff | 214 days |
| Structure | Pre-Acquisition Spin |
| Parent | Avidity Bio (RNA) |
| Day-1 reaction | |
| Day 1 open | $14.58 |
| Day 1 return (open→close) | +1.2% |
| Day 1 price (close) | $14.75 |
| Day 1 range | $13.06 – $15.93 +22.0% spread |
| Day 1 low held? | Breached after 13 sessions to -38.0% below |
| Price levels | |
| Post-spin low (closing) | $8.19 on Sep 24, 2026 · 209 days post-spin |
| Lowest traded | $8.10 on Sep 25, 2026 · 210 days post-spin |
| Current price (Sep 25, 2026) | $8.29 |
| Returns | |
| Return vs Day 1 (close) | -43.8% |
| — range by day 1 entry theoretical bounds | -48.0% to -36.5% |
| Return vs post-spin low | +1.2% |
| First-quarter return (≈90d) | -9.4% |
| Versus benchmarks | |
| S&P 500 over same window | +13.3% |
| Shares & ownership | |
| Shares outstanding Mar 31, 2026 | 17,105,643 |
| Diluted average shares the EPS denominator | 17,105,643 |
| Free float | 15,043,558 88% of shares outstanding |
| Held by institutions | 84% insiders 4.2% |
| Share count trend Dec 2024 → Mar 2026 | +0.0% broadly flat |
| Volume & liquidity | |
| Traded per day 20-session median | $2.69M |
| Normal volume baseline | 196,750 shares · now 1.35x |
| Day 1 volume | 40.5x normal · first week 18.0x |
| Decay | half in 2 sessions · normal by 26 |
Computed from split-adjusted closing prices. Returns are total return — (end price + dividends received − start price) ÷ start price — with no reinvestment assumed.
Price History
Closing price, split-adjusted, with volume below. No dividends have been paid, so price return and total return are the same. Source: Yahoo Finance. Data through Sep 26, 2026.
Raw daily price & volume data
| Date | Open | High | Low | Close | Volume | Float | Turnover | Market cap | Dividend | Split |
|---|---|---|---|---|---|---|---|---|---|---|
| 2026-09-25 | $8.20 | $8.37 | $8.10 | $8.29 | 221,400 | 15,043,558 | 1.29% | $142M | — | — |
| 2026-09-24 | $8.30 | $8.49 | $8.16 | $8.19 | 355,100 | 15,043,558 | 2.08% | $140M | — | — |
| 2026-09-23 | $9.22 | $9.31 | $8.29 | $8.33 | 434,000 | 15,043,558 | 2.54% | $142M | — | — |
| 2026-09-22 | $9.24 | $9.49 | $9.17 | $9.22 | 241,300 | 15,043,558 | 1.41% | $158M | — | — |
| 2026-09-21 | $8.97 | $9.34 | $8.94 | $9.19 | 481,300 | 15,043,558 | 2.81% | $157M | — | — |
| 2026-09-18 | $9.57 | $9.67 | $8.66 | $8.95 | 1,036,600 | 15,043,558 | 6.06% | $153M | — | — |
| 2026-09-17 | $9.65 | $9.70 | $9.44 | $9.56 | 569,600 | 15,085,124 | 3.33% | $164M | — | — |
| 2026-09-16 | $10.11 | $10.11 | $9.50 | $9.50 | 356,400 | 15,085,124 | 2.08% | $163M | — | — |
| 2026-09-15 | $10.21 | $10.21 | $9.62 | $10.09 | 274,600 | 15,085,124 | 1.61% | $173M | — | — |
| 2026-09-14 | $10.37 | $10.71 | $10.15 | $10.21 | 255,700 | 15,085,124 | 1.49% | $175M | — | — |
| 2026-09-11 | $10.37 | $10.41 | $10.00 | $10.36 | 247,400 | 15,085,124 | 1.45% | $177M | — | — |
| 2026-09-10 | $10.44 | $10.74 | $10.28 | $10.35 | 421,600 | 15,085,124 | 2.46% | $177M | — | — |
| 2026-09-09 | $11.20 | $11.20 | $10.34 | $10.51 | 690,300 | 15,085,124 | 4.04% | $180M | — | — |
| 2026-09-08 | $14.08 | $14.19 | $10.75 | $11.35 | 1,719,500 | 15,085,124 | 10.05% | $194M | — | — |
| 2026-09-04 | $14.51 | $14.65 | $14.01 | $14.19 | 167,800 | 15,085,124 | 0.98% | $243M | — | — |
| 2026-09-03 | $14.19 | $14.68 | $13.99 | $14.60 | 164,900 | 15,085,124 | 0.96% | $250M | — | — |
| 2026-09-02 | $13.77 | $14.10 | $13.76 | $14.06 | 111,600 | 15,085,124 | 0.65% | $241M | — | — |
| 2026-09-01 | $13.24 | $13.92 | $13.20 | $13.77 | 178,300 | 15,085,124 | 1.04% | $236M | — | — |
| 2026-08-31 | $13.53 | $13.55 | $13.10 | $13.32 | 97,000 | 15,085,124 | 0.57% | $228M | — | — |
| 2026-08-28 | $13.87 | $13.95 | $13.51 | $13.64 | 108,600 | 15,085,124 | 0.63% | $233M | — | — |
| 2026-08-27 | $13.78 | $14.09 | $13.59 | $13.98 | 120,500 | 15,085,124 | 0.70% | $239M | — | — |
| 2026-08-26 | $13.93 | $14.07 | $13.66 | $13.85 | 179,300 | 15,085,124 | 1.05% | $237M | — | — |
| 2026-08-25 | $13.72 | $14.05 | $13.41 | $14.00 | 166,600 | 15,085,124 | 0.97% | $239M | — | — |
| 2026-08-24 | $13.27 | $13.64 | $13.04 | $13.62 | 140,500 | 15,085,124 | 0.82% | $233M | — | — |
| 2026-08-21 | $13.53 | $13.59 | $12.96 | $13.20 | 180,700 | 15,085,124 | 1.06% | $226M | — | — |
| 2026-08-20 | $13.75 | $13.88 | $13.20 | $13.48 | 218,800 | 15,085,124 | 1.28% | $231M | — | — |
| 2026-08-19 | $13.00 | $13.72 | $12.85 | $13.71 | 360,300 | 15,085,124 | 2.11% | $235M | — | — |
| 2026-08-18 | $12.91 | $12.96 | $12.72 | $12.84 | 107,900 | 15,085,124 | 0.63% | $220M | — | — |
| 2026-08-17 | $12.78 | $13.35 | $12.78 | $12.96 | 212,600 | 15,085,124 | 1.24% | $222M | — | — |
| 2026-08-14 | $12.21 | $12.97 | $12.08 | $12.84 | 176,100 | 15,085,124 | 1.03% | $220M | — | — |
| 2026-08-13 | $12.21 | $12.46 | $12.03 | $12.33 | 127,100 | — | 0.74% | $211M | — | — |
| 2026-08-12 | $12.27 | $12.35 | $12.06 | $12.17 | 84,200 | — | 0.49% | $208M | — | — |
| 2026-08-11 | $12.25 | $12.44 | $12.20 | $12.27 | 84,200 | — | 0.49% | $210M | — | — |
| 2026-08-10 | $12.25 | $12.44 | $12.20 | $12.24 | 109,000 | — | 0.64% | $209M | — | — |
| 2026-08-07 | $12.15 | $12.49 | $12.15 | $12.34 | 103,300 | — | 0.60% | $211M | — | — |
| 2026-08-06 | $11.96 | $12.31 | $11.88 | $12.11 | 193,100 | — | 1.13% | $207M | — | — |
| 2026-08-05 | $11.53 | $11.99 | $11.46 | $11.74 | 171,900 | — | 1.00% | $201M | — | — |
| 2026-08-04 | $11.40 | $11.74 | $11.35 | $11.54 | 137,000 | — | 0.80% | $197M | — | — |
| 2026-08-03 | $11.45 | $11.53 | $11.30 | $11.33 | 91,500 | — | 0.53% | $194M | — | — |
| 2026-07-31 | $11.44 | $11.54 | $11.20 | $11.35 | 116,300 | — | 0.68% | $194M | — | — |
| 2026-07-30 | $11.19 | $11.55 | $11.19 | $11.46 | 91,800 | — | 0.54% | $196M | — | — |
| 2026-07-29 | $11.46 | $11.46 | $11.13 | $11.18 | 119,400 | — | 0.70% | $191M | — | — |
| 2026-07-28 | $11.59 | $11.63 | $11.36 | $11.49 | 91,900 | — | 0.54% | $197M | — | — |
| 2026-07-27 | $11.61 | $11.80 | $11.46 | $11.57 | 82,800 | — | 0.48% | $198M | — | — |
| 2026-07-24 | $11.98 | $11.98 | $11.48 | $11.49 | 120,900 | — | 0.71% | $197M | — | — |
| 2026-07-23 | $12.00 | $12.14 | $11.78 | $11.91 | 101,300 | — | 0.59% | $204M | — | — |
| 2026-07-22 | $12.28 | $12.35 | $12.09 | $12.17 | 99,900 | — | 0.58% | $208M | — | — |
| 2026-07-21 | $11.73 | $12.35 | $11.61 | $12.29 | 181,900 | — | 1.06% | $210M | — | — |
| 2026-07-20 | $12.14 | $12.15 | $11.75 | $11.76 | 186,100 | — | 1.09% | $201M | — | — |
| 2026-07-17 | $12.01 | $12.30 | $11.97 | $12.15 | 122,200 | — | 0.71% | $208M | — | — |
| 2026-07-16 | $12.29 | $12.29 | $11.93 | $12.16 | 182,700 | — | 1.07% | $208M | — | — |
| 2026-07-15 | $12.26 | $12.40 | $12.05 | $12.30 | 88,800 | — | 0.52% | $210M | — | — |
| 2026-07-14 | $12.26 | $12.47 | $12.05 | $12.22 | 208,100 | — | 1.22% | $209M | — | — |
| 2026-07-13 | $12.40 | $12.59 | $12.21 | $12.22 | 178,900 | — | 1.05% | $209M | — | — |
| 2026-07-10 | $12.87 | $12.87 | $12.20 | $12.46 | 319,900 | — | 1.87% | $213M | — | — |
| 2026-07-09 | $13.40 | $13.44 | $12.75 | $12.91 | 239,500 | — | 1.40% | $221M | — | — |
| 2026-07-08 | $13.07 | $13.38 | $12.86 | $13.37 | 203,200 | — | 1.19% | $229M | — | — |
| 2026-07-07 | $13.14 | $13.36 | $12.95 | $13.24 | 257,300 | — | 1.50% | $226M | — | — |
| 2026-07-06 | $13.60 | $13.61 | $12.76 | $13.01 | 206,700 | — | 1.21% | $223M | — | — |
| 2026-07-02 | $13.40 | $13.72 | $13.20 | $13.65 | 196,900 | — | 1.15% | $233M | — | — |
| 2026-07-01 | $13.43 | $13.80 | $13.26 | $13.30 | 150,400 | — | 0.88% | $228M | — | — |
| 2026-06-30 | $13.67 | $13.80 | $13.22 | $13.45 | 316,800 | — | 1.85% | $230M | — | — |
| 2026-06-29 | $13.20 | $13.80 | $13.20 | $13.65 | 382,200 | — | 2.23% | $233M | — | — |
| 2026-06-26 | $12.78 | $13.20 | $12.72 | $13.19 | 758,700 | — | 4.44% | $226M | — | — |
| 2026-06-25 | $12.93 | $13.07 | $12.70 | $12.78 | 262,200 | — | 1.53% | $219M | — | — |
| 2026-06-24 | $12.86 | $13.00 | $12.74 | $12.83 | 123,400 | — | 0.72% | $219M | — | — |
| 2026-06-23 | $12.89 | $13.14 | $12.76 | $12.81 | 242,400 | — | 1.42% | $219M | — | — |
| 2026-06-22 | $12.65 | $12.96 | $12.59 | $12.94 | 220,800 | — | 1.29% | $221M | — | — |
| 2026-06-18 | $12.83 | $12.96 | $12.20 | $12.66 | 294,100 | — | 1.72% | $217M | — | — |
| 2026-06-17 | $12.73 | $12.83 | $12.28 | $12.48 | 190,300 | — | 1.11% | $213M | — | — |
| 2026-06-16 | $12.75 | $12.75 | $12.40 | $12.61 | 160,500 | — | 0.94% | $216M | — | — |
| 2026-06-15 | $12.40 | $12.76 | $12.30 | $12.75 | 261,500 | — | 1.53% | $218M | — | — |
| 2026-06-12 | $12.43 | $12.47 | $12.16 | $12.37 | 103,600 | — | 0.61% | $212M | — | — |
| 2026-06-11 | $11.69 | $12.53 | $11.40 | $12.43 | 328,700 | — | 1.92% | $213M | — | — |
| 2026-06-10 | $11.86 | $11.99 | $11.64 | $11.67 | 136,600 | — | 0.80% | $200M | — | — |
| 2026-06-09 | $11.60 | $11.89 | $11.45 | $11.76 | 201,700 | — | 1.18% | $201M | — | — |
| 2026-06-08 | $11.90 | $11.91 | $11.48 | $11.55 | 126,100 | — | 0.74% | $198M | — | — |
| 2026-06-05 | $12.30 | $12.38 | $11.77 | $11.80 | 209,400 | — | 1.22% | $202M | — | — |
| 2026-06-04 | $12.26 | $12.62 | $12.17 | $12.30 | 126,100 | — | 0.74% | $210M | — | — |
| 2026-06-03 | $12.27 | $12.39 | $12.12 | $12.17 | 150,100 | — | 0.88% | $208M | — | — |
| 2026-06-02 | $12.59 | $12.59 | $12.20 | $12.25 | 180,700 | — | 1.06% | $210M | — | — |
| 2026-06-01 | $13.00 | $13.10 | $12.35 | $12.68 | 209,600 | — | 1.23% | $217M | — | — |
| 2026-05-29 | $13.27 | $13.60 | $12.94 | $13.00 | 321,300 | — | 1.88% | $222M | — | — |
| 2026-05-28 | $13.10 | $14.14 | $12.97 | $13.36 | 345,200 | — | 2.02% | $229M | — | — |
| 2026-05-27 | $13.08 | $13.12 | $12.93 | $13.00 | 169,200 | — | 0.99% | $222M | — | — |
| 2026-05-26 | $13.20 | $13.29 | $12.95 | $13.06 | 170,900 | — | 1.00% | $223M | — | — |
| 2026-05-22 | $13.01 | $13.28 | $12.98 | $13.09 | 292,200 | — | 1.71% | $224M | — | — |
| 2026-05-21 | $12.61 | $13.13 | $12.61 | $13.04 | 252,400 | — | 1.48% | $223M | — | — |
| 2026-05-20 | $12.94 | $13.01 | $12.61 | $12.72 | 168,100 | — | 0.98% | $218M | — | — |
| 2026-05-19 | $12.96 | $13.20 | $12.74 | $12.95 | 273,100 | — | 1.60% | $222M | — | — |
| 2026-05-18 | $13.24 | $13.57 | $12.85 | $12.95 | 147,200 | — | 0.86% | $222M | — | — |
| 2026-05-15 | $13.48 | $13.97 | $13.04 | $13.23 | 234,300 | — | 1.37% | $226M | — | — |
| 2026-05-14 | $13.27 | $13.51 | $13.00 | $13.27 | 100,300 | — | 0.59% | $227M | — | — |
| 2026-05-13 | $13.11 | $13.30 | $12.91 | $13.30 | 100,700 | — | 0.59% | $228M | — | — |
| 2026-05-12 | $13.34 | $13.40 | $13.06 | $13.14 | 179,500 | — | 1.05% | $225M | — | — |
| 2026-05-11 | $13.08 | $13.50 | $13.07 | $13.25 | 169,900 | — | 0.99% | $227M | — | — |
| 2026-05-08 | $12.88 | $13.19 | $12.84 | $13.07 | 109,800 | — | 0.64% | $224M | — | — |
| 2026-05-07 | $13.07 | $13.20 | $12.80 | $12.96 | 189,100 | — | 1.11% | $222M | — | — |
| 2026-05-06 | $12.94 | $13.30 | $12.80 | $13.09 | 277,600 | — | 1.62% | $224M | — | — |
| 2026-05-05 | $12.93 | $13.04 | $12.75 | $12.91 | 321,000 | — | 1.88% | $221M | — | — |
| 2026-05-04 | $13.30 | $13.57 | $12.81 | $12.87 | 144,500 | — | 0.84% | $220M | — | — |
| 2026-05-01 | $12.76 | $13.48 | $12.76 | $13.43 | 169,400 | — | 0.99% | $230M | — | — |
| 2026-04-30 | $13.00 | $13.49 | $12.71 | $12.77 | 252,100 | — | 1.47% | $218M | — | — |
| 2026-04-29 | $12.50 | $13.06 | $12.50 | $12.99 | 162,600 | — | 0.95% | $222M | — | — |
| 2026-04-28 | $13.00 | $13.00 | $12.51 | $12.55 | 452,500 | — | 2.65% | $215M | — | — |
| 2026-04-27 | $13.59 | $13.66 | $12.79 | $12.90 | 287,700 | — | 1.68% | $221M | — | — |
| 2026-04-24 | $13.78 | $13.78 | $13.46 | $13.49 | 196,600 | — | 1.15% | $231M | — | — |
| 2026-04-23 | $14.01 | $14.80 | $13.68 | $13.85 | 511,000 | — | 2.99% | $237M | — | — |
| 2026-04-22 | $13.61 | $13.92 | $13.50 | $13.66 | 583,700 | — | 3.41% | $234M | — | — |
| 2026-04-21 | $14.24 | $14.30 | $13.51 | $13.53 | 519,500 | — | 3.04% | $231M | — | — |
| 2026-04-20 | $14.42 | $14.50 | $14.20 | $14.30 | 548,000 | — | 3.20% | $245M | — | — |
| 2026-04-17 | $13.99 | $14.63 | $13.99 | $14.41 | 632,800 | — | 3.70% | $246M | — | — |
| 2026-04-16 | $14.46 | $14.51 | $13.88 | $14.03 | 275,100 | — | 1.61% | $240M | — | — |
| 2026-04-15 | $14.00 | $14.60 | $13.91 | $14.54 | 568,300 | — | 3.32% | $249M | — | — |
| 2026-04-14 | $13.31 | $14.05 | $13.18 | $14.02 | 670,500 | — | 3.92% | $240M | — | — |
| 2026-04-13 | $12.66 | $13.32 | $12.66 | $13.30 | 1,453,800 | — | 8.50% | $228M | — | — |
| 2026-04-10 | $13.64 | $13.80 | $12.63 | $12.71 | 1,028,000 | — | 6.01% | $217M | — | — |
| 2026-04-09 | $13.71 | $13.93 | $13.60 | $13.72 | 219,200 | — | 1.28% | $235M | — | — |
| 2026-04-08 | $14.00 | $14.18 | $13.54 | $13.70 | 213,900 | — | 1.25% | $234M | — | — |
| 2026-04-07 | $13.61 | $14.00 | $13.56 | $13.99 | 234,900 | — | 1.37% | $239M | — | — |
| 2026-04-06 | $13.44 | $13.92 | $13.44 | $13.67 | 172,900 | — | 1.01% | $234M | — | — |
| 2026-04-02 | $13.40 | $13.71 | $13.31 | $13.44 | 281,700 | — | 1.65% | $230M | — | — |
| 2026-04-01 | $13.36 | $13.90 | $13.36 | $13.47 | 304,200 | — | 1.78% | $230M | — | — |
| 2026-03-31 | $13.41 | $13.53 | $13.06 | $13.37 | 921,400 | — | 5.39% | $229M | — | — |
| 2026-03-30 | $13.16 | $13.60 | $13.00 | $13.55 | 566,700 | — | 3.31% | $232M | — | — |
| 2026-03-27 | $13.00 | $13.28 | $12.90 | $13.23 | 410,800 | — | 2.40% | $226M | — | — |
| 2026-03-26 | $12.99 | $13.25 | $12.95 | $13.10 | 231,000 | — | 1.35% | $224M | — | — |
| 2026-03-25 | $13.41 | $13.41 | $12.77 | $13.09 | 292,500 | — | 1.71% | $224M | — | — |
| 2026-03-24 | $13.18 | $13.50 | $13.11 | $13.20 | 1,209,900 | — | 7.07% | $226M | — | — |
| 2026-03-23 | $13.21 | $13.50 | $12.99 | $13.20 | 408,100 | — | 2.39% | $226M | — | — |
| 2026-03-20 | $12.67 | $13.28 | $12.33 | $13.13 | 1,119,300 | — | 6.54% | $225M | — | — |
| 2026-03-19 | $12.30 | $12.87 | $11.95 | $12.69 | 566,600 | — | 3.31% | $217M | — | — |
| 2026-03-18 | $13.76 | $13.76 | $12.29 | $12.32 | 1,758,600 | — | 10.28% | $211M | — | — |
| 2026-03-17 | $13.74 | $13.89 | $13.61 | $13.77 | 308,200 | — | 1.80% | $236M | — | — |
| 2026-03-16 | $13.77 | $13.99 | $13.65 | $13.79 | 254,400 | — | 1.49% | $236M | — | — |
| 2026-03-13 | $14.47 | $14.55 | $13.57 | $13.75 | 692,400 | — | 4.05% | $235M | — | — |
| 2026-03-12 | $14.70 | $14.76 | $14.42 | $14.54 | 467,800 | — | 2.73% | $249M | — | — |
| 2026-03-11 | $14.70 | $15.84 | $14.60 | $14.80 | 738,800 | — | 4.32% | $253M | — | — |
| 2026-03-10 | $14.82 | $15.34 | $14.60 | $14.67 | 752,400 | — | 4.40% | $251M | — | — |
| 2026-03-09 | $14.59 | $15.01 | $14.00 | $14.79 | 829,200 | — | 4.85% | $253M | — | — |
| 2026-03-06 | $15.26 | $15.79 | $14.71 | $14.82 | 1,117,200 | — | 6.53% | $254M | — | — |
| 2026-03-05 | $16.61 | $16.77 | $15.25 | $15.47 | 1,623,700 | — | 9.49% | $265M | — | — |
| 2026-03-04 | $15.32 | $16.57 | $15.32 | $16.54 | 2,002,900 | — | 11.71% | $283M | — | — |
| 2026-03-03 | $14.70 | $15.89 | $14.44 | $15.67 | 2,895,000 | — | 16.92% | $268M | — | — |
| 2026-03-02 | $13.81 | $15.51 | $13.81 | $14.91 | 3,208,700 | — | 18.76% | $255M | — | — |
| 2026-02-27 | $14.58 | $15.93 | $13.06 | $14.75 | 7,963,600 | — | 46.56% | $252M | — | — |
Close is split-adjusted to current shares. It is not dividend-adjusted: dividends are listed separately, so total return is (end price + dividends received − start price) ÷ start price, checkable by hand. Volume is as-traded.
Post Spin Analysis
Completed Feb 26, 2026. Spun ahead of Novartis $12B acquisition of parent.
Compiled from tracked data as of the July 31, 2026 close.
The move
Atrium Therapeutics separated from Avidity Bio (RNA) on February 26, 2026 as a pre-acquisition spin, listing on Nasdaq. It closed its first regular-way session at $14.75 and set a post-spin low of $11.18 on Jul 29, 2026, 151 days after the spin. It last traded at $11.35 (Jul 31, 2026), -23.1% against the Day-1 close and +1.5% off the low.
The low came 151 days out — well beyond the usual forced-selling window, which points at something structural rather than mechanical selling pressure.
What we graded it
Covered in a single report before separation. Current rating: SPECULATIVE.
⚠ Auto-generated profile — not editorially reviewed.
This summary is compiled automatically from our tracked report data. A reviewed in-depth profile is planned. For further detail ▸ read the May 31, 2026 report.