4DMedical has spent the last three months proving that even CE Mark approvals 1 and GlaxoSmithKline imaging contracts 2 cannot protect a stock from dilution gravity. While the company expanded its addressable market 3, short sellers quietly built a position that now sits well above the sector average.
The inflection point came in April 2026, when an A$83 million equity raise 1 was followed by a steady stream of proposed security issues 456. For retail investors, the clinical milestones—like lifting lung surgery success rates 7 or entering the CT:VQ market 8—suggested momentum. For short sellers, the constant issuance of new paper 9101112 provided the perfect setup. Dilution fears culminated on 10 June 2026, when the share price fell nearly 9% in a single session 13 as the market struggled to digest the expanding register.
The data shows a rapid shift in sentiment. Short interest in 4DX has climbed from a 90-day average of 3.74% to 10.95% today, representing a 7.21 percentage-point increase over the period. This aggressive shorting campaign has run parallel to a 15.1% slide in the share price over the past three months. The 30-day price-to-short correlation of 0.433 indicates that the build-up was highly structured rather than a sudden reaction. With the peer sector short average sitting at 6.82%, 4DMedical has become a clear outlier.
Clinical progress is rarely a straight line, but when it is funded by continuous dilution, the market tends to price the paper before the technology. The short position suggests the discounting is not finished yet.