6 US-stock research checks for UK investors

1. Confirm the issuer, exchange and share class#

Record the legal company name and instrument. Ordinary shares, preferred shares and depositary receipts can carry different economic or voting rights. Use the issuer's verified investor-relations materials and SEC filings to establish what the US-listed security actually represents.

2. Check whether an ADR represents multiple shares#

An American depositary receipt (ADR) can represent one underlying share, several shares or a fraction. The SEC's ADR bulletin explains this structure. Check that ratio before comparing its price with an ordinary share; otherwise you may mistake a different number of shares for a discount. Read the deposit agreement and applicable fees too. A rights issue can present different practical choices for an ordinary-share holder and an ADR holder.

3. Separate trading currency from business exposure#

Check which currencies the company earns revenue and pays costs in, as well as the quote currency and the currency you use to measure your own results. Those exposures can differ. The SEC's international-investing guide explains currency and other cross-border risks that remain after you convert a share price.

4. Align financial periods and accounting labels#

Two “2025” reports can end in different months. Compare actual period boundaries and note whether the issuer uses US GAAP or another accounting framework. Foreign private issuers may file an annual 20-F and furnish information on 6-K rather than follow the domestic 10-Q pattern. Do not infer missing results from the wrong form filter.

5. Check the market-data timestamp#

Write down whether you are using a regular-session close, an intraday quote or an after-hours price. NYSE and Nasdaq list the main US equity session as 9:30 a.m. to 4:00 p.m. Eastern Time. That is normally 2:30 to 9:00 p.m. UK time when both countries are on summer time or both are on standard time. In the short spring period after the US changes clocks first, and the autumn period after the UK changes back first, it is 1:30 to 8:00 p.m. UK time.

The exact mismatch weeks change by year. In 2026, NIST gives the US changes as 8 March and 1 November; GOV.UK gives the UK changes as 29 March and 25 October. A US regular-session close on 20 March 2026 therefore corresponds to 8:00 p.m. in the UK, an hour earlier than usual. Check the exchange holiday and early-close calendar too. Keep the quote's timestamp, timezone and session with any calculation that uses it.

6. Verify access, fees and tax questions separately#

A research tool and a brokerage serve different jobs. Before assuming you can hold a security in your account, ask the broker about availability, account eligibility, charges and currency conversion. Check ISA eligibility and tax questions separately with the broker or a qualified professional; a company-research page cannot settle them.

Example: comparing an ADR with its underlying shares#

Suppose one ADR represents two ordinary shares. Each ordinary share is quoted at £20, and the exchange rate is $1.25 per £1. The equivalent underlying value is 2 × £20 × 1.25 = $50 per ADR before fees and market differences. Comparing the ADR with $25 would forget half of the underlying shares.

Once the ratio is correct, check whether trading times and fees explain any remaining gap. Keep the ratio source and exchange-rate date with your calculation. See seven valuation mistakes for other comparison errors.