Is Castle Biosciences (CSTL) stock Halal?

Castle Biosciences is a **molecular diagnostics company** specializing in genomic tests that inform clinical decision-making in dermatology, ophthalmology, and gastroenterology. Its portfolio includes proprietary gene expression profile assays such as DecisionDx-Melanoma and DecisionDx-SCC, which assess metastatic risk in skin cancers, DecisionDx-UM for uveal melanoma staging, MyPath Melanoma for lesion characterization, and TissueCypher for predicting progression risk in Barrett’s esophagus. For Muslim investors, though, the most pressing question is simpler: is Castle Biosciences a Halal investment?

Is Castle Biosciences Shariah compliant?

No. In the October 2026 screening Castle Biosciences (CSTL) does not pass AAOIFI screening: it fails the interest-bearing investments screen. Medicines and medical devices are permissible, and healthcare companies like Castle Biosciences usually clear the activity screen comfortably. What AAOIFI Shariah Standard No. 21 watches is the financing behind the pipeline: drug development is expensive, and the 30% interest bearing debt cap decides the verdict more often than the science does.

Does Castle Biosciences pass the business activity test?

The activity screen is only part of the picture this month: Castle Biosciences currently fails the interest-bearing investments screen, so the overall verdict is not compliant regardless of the business itself. Treating illness is permissible work; the scrutiny belongs to the financing behind it.

Is Castle Biosciences' income Halal?

Yes, within AAOIFI's tolerance. Castle Biosciences' income from non-permissible sources stays below 5% of revenue in the October 2026 screening.

Does Castle Biosciences meet AAOIFI's debt and investment ratio requirements?

Not in full. Interest bearing investments currently exceed the 30% cap, measured against a market capitalisation of $1.09B (market data as of 1 October 2026), while the other ratio stays within it. One breach is enough to fail the screening; the ratios are reassessed monthly under our Shariah Supervisory Board.

Why do other halal screeners show a different verdict for Castle Biosciences?

Screeners can disagree without either being wrong. AAOIFI Shariah Standard No. 21, which Tabadulat applies, measures interest bearing debt and investments against market capitalisation with a 30% ceiling. MSCI and FTSE measure them against total assets with a 33% ceiling, and S&P and Dow Jones Islamic use a multi year average of market capitalisation. Data dates differ too, because each provider reads filings and prices on its own schedule. The same company can therefore pass one standard and fail another in the same month. Tabadulat publishes one answer, the AAOIFI result as of October 2026, and re-screens it every month.

Tabadulat is an ADGM regulated brokerage whose license covers Shari'a Compliant Regulated Activities, as the FSRA permission names them. New to the terminology? Gharar and Maysir, Sukuk, Zakat and purification are all explained in plain English.

New to the screening method? Read What is Halal Investing? A Guide to Halal Stocks and Islamic Finance