Why Quantum Computing Stock Xanadu Quantum Technologies Plummeted 56.2% in September

XNDU plunged 56.2% in September 2026, with the selloff tied primarily to the September 22 expiration of a post-merger lockup period. The expiry freed early investors and insiders to sell shares, and the stock absorbed the supply.

The drop came despite constructive company news. XNDU announced collaborations with ASML and AMD, two named industry heavyweights, during the month. Interpretation: the partnership headlines did not offset selling pressure from newly unrestricted holders, which suggests supply mechanics outweighed fundamental news flow in September.

Sell-side sentiment stayed positive. RBC Capital rates XNDU outperform with a $16 price target. Interpretation: the analyst view diverged sharply from the month's price action, leaving a gap between the Street's stated valuation and where the stock traded after the lockup event.

The setup pits a 56.2% monthly decline against two collaboration announcements and an outperform rating. Traders now have to decide whether the lockup expiry was a one-time supply shock that has largely run its course, or whether insider and early-investor selling remains a headwind for the stock.