ADR and CDI Basics: How Cross-Listed Stocks Work

Hundreds of major companies trade in two places at once: home shares on their local exchange and a second line (an ADR in New York, or a CDI in Sydney) for investors elsewhere. Same company, same claim on the same cash flows, two tickers, two currencies, two prices. This guide covers the mechanics: ratios, FX normalization, parity, and why the two prices never quite agree.

What an ADR actually is

An American Depositary Receipt is a U.S.-traded certificate representing a fixed number of a foreign company’s home-market shares. A depositary bank (JPMorgan, BNY Mellon, Citi, Deutsche Bank) holds the underlying shares in custody in the home market and issues receipts against them that trade in U.S. dollars, settle in U.S. systems, and pay dividends in dollars after conversion. You own economic exposure to the foreign shares without touching a foreign brokerage account.

The critical number is the ratio: how many home shares one ADR represents. It is set per program and can be anything: 1:1, 1:2, 1:8, or inverted (one ADR = one-tenth of a share) for stocks with very high home-market prices. The ratio exists mostly to land the ADR in the $20–$200 price range U.S. investors expect, and it can change: a program can re-ratio, which moves the ADR price overnight without any change in value. Always check the current ratio before comparing prices across listings.

One more distinction worth knowing: sponsored ADRs are established with the company’s cooperation (the company appoints the depositary; larger programs list on NYSE/Nasdaq and file with the SEC), while unsponsored ADRs are created by banks without company involvement and trade over the counter, often with thinner disclosure and multiple parallel programs. Depositary banks also charge pass-through fees (custody and dividend-processing charges, typically a few cents per share per year) that home-market holders don’t pay.

CDIs: the Australian variation

A CHESS Depositary Interest is the same idea adapted to Australia’s settlement system. Foreign-incorporated companies can’t settle directly in CHESS (the ASX’s clearing system), so investors instead trade CDIs: beneficial interests in the underlying foreign shares, held via a depositary nominee. Like ADRs, CDIs have a ratio: some are 1:1, but many are not (ratios like 3:1 or 10:1 CDIs per share are common), and dual-listed names with a U.S. primary listing often trade in Sydney as CDIs priced in Australian dollars. The mechanics of comparing a CDI line to a U.S. line are identical to the ADR case: adjust for the ratio, then for the currency.

Parity: the number everything is measured against

Because both lines represent the same underlying shares, there is a mechanical “correct” relationship between their prices, called parity:

Parity price = home share price × depositary ratio × FX rate

That is the home price, converted into the second listing’s currency and scaled by how many home shares the receipt represents. The gap between the receipt’s actual traded price and its parity price is the premium (trading above parity) or discount (below). This is the single number that makes two listings comparable, and computing it correctly (fresh FX, current ratio) is exactly what the Compare tool automates.

Why the two prices disagree, and why gaps persist

In a frictionless world, arbitrage would pin every receipt to parity: ADRs are convertible (a broker can cancel receipts and take delivery of home shares, or deposit home shares to create new receipts), so any gap is theoretically free money. In practice, gaps of a fraction of a percent are routine and larger ones appear regularly, because the arbitrage has real costs and constraints:

• Time zones. Sydney and London are closed while New York trades. Most of the time, one price is live and the other is stale; much of any apparent spread is just the U.S. market’s ongoing opinion of news the home market hasn’t opened to price yet.
• Conversion frictions. Creating or canceling receipts costs depositary fees, settlement time, and FX execution: a floor below which small gaps aren’t worth closing.
• Liquidity differences. A thin line moves more per dollar traded. Where one listing dominates volume, the quiet line drifts around parity between arbitrage passes.
• Structural constraints. Some markets restrict foreign ownership or make conversion one-directional; in those programs premiums can persist for months because the closing trade simply isn’t available.

For a long-term holder, the practical significance is modest but real: which line you buy determines the currency of your dividends, the depositary fees you pay, your tax paperwork, and, if you buy into a premium that later closes, a headwind unrelated to the company. Checking the spread before choosing a line is a sixty-second errand (it is the last station of how to research a stock in 15 minutes).

A pre-trade checklist for cross-listed names

1. Confirm the current ratio from the depositary or the company’s IR page, not from memory, since programs re-ratio.
2. Compute parity with a fresh FX rate, or let Compare do it; it normalizes currency and ratio and charts the premium/discount through time, which shows whether today’s gap is typical or an outlier for that pair.
3. Check both lines’ liquidity: spreads and depth can differ enormously between a home line and its receipt.
4. Price in the frictions: depositary fees, dividend conversion, and any withholding-tax differences between holding routes.