Shares you trade are counted at full market value. For long-term holdings, zakat is due on your share of each company's zakatable assets; when that is hard to find, the National Zakat Foundation suggests counting 25% of the market value.
Trading or investing
If you bought shares to sell, count their full market value on your zakat date. If you hold them long term for dividends, zakat is due on your portion of the zakatable assets (such as cash and stock) inside each company, not on the full share price.
The 25% shortcut
Company accounts are hard to read, so the National Zakat Foundation's guide offers a rule of thumb for long-term holdings: take 25% of the portfolio's market value and pay 2.5% of that. Its separate guide to missed zakat in past years uses 40% for the same purpose, so ask a scholar which to use for your case. The calculator offers full value or 25%.
Zaytuna College's calculator counts the current value of shares that are permissible to own.
ISAs and funds
A stocks-and-shares ISA you are not planning to sell is treated like long-term shares: zakat on your share of the companies' zakatable assets. Tools such as Zoya work this out stock by stock.
Worked example: £40,000 long-term portfolio using the 25% shortcut
Shares (25%)
£10,000.00
Zakatable wealth
£10,000.00
Zakat (2.5%)
£250.00
25% of £40,000 = £10,000 zakatable; 2.5% of that = £250. Prices: gold £90.80/g, silver £1.25/g (National Zakat Foundation nisab page, 17 October 2026); silver nisab £765.45 (612.36 g).
Only for shares you trade. For long-term holdings it is 2.5% of your share of the companies' zakatable assets, which the 25% shortcut approximates (National Zakat Foundation).
Why do some guides say 40% instead of 25%?
The National Zakat Foundation's guide to missed zakat for past years uses 40% as the proxy; its main guide uses 25%. A scholar can say which suits you.
Based on: NZF-G p4-5; NZF-M p7; ZAY (see sources and method). An estimate, not a fatwa: ask a scholar about your own situation.