Investment fund RTW Biotech Opportunities Ltd (LSE: RTW) reported on Monday that its portfolio company Avidity Biosciences Inc (Nasdaq: RNA) has agreed to be acquired by Novartis AG (SWX: NOVN) for USD72 per share in cash, valuing the clinical-stage biotech at approximately USD12bn on a fully diluted basis.

The offer represents a 46% premium to Avidity's closing share price on 24 October 2025 and a 62% premium to its 30-day volume-weighted average price. As at 30 September 2025, Avidity was RTW Bio's third-largest holding, accounting for 7.0% of net asset value.

Avidity develops RNA therapeutics and has three clinical-stage programmes targeting rare muscle diseases. Its lead candidate, del-desiran, is in Phase 3 trials for DM1. The company pioneered targeted RNA delivery into muscle tissue and is expanding its pipeline into cardiology and immunology.

Before completion, Avidity will transfer its early-stage precision cardiology assets to a new subsidiary, SpinCo. Shareholders will receive one SpinCo share for every ten Avidity shares held, or a pro rata cash distribution if SpinCo or its assets are sold. SpinCo is expected to trade as an independent public company following the spin-off.