Both Taiwan Semiconductor Manufacturing Company (NYSE: TSM) and SK hynix (Nasdaq: SKHY) sell U.S.-listed depositary shares that sit on top of an Asia-listed ordinary share. Both therefore display an "ADR premium" — the gap between the New York price and the currency-adjusted home-market price. But the two securities are at very different stages of that relationship, and comparing them clarifies what a depositary-receipt premium actually measures.
TSMC's ADR has traded since 1997 and is one of the most studied depositary receipts in the world. SKHY listed on July 10, 2026, and its first 11 sessions produced a matched-close premium ranging from 15.8% to 51.1%.[1] Reading the new listing against the established one separates durable features of ADR pricing from debut-period noise.
Same structure, different ratios
An ADR premium is only meaningful once the U.S. share and the home-market share describe the same ownership. Both TSM and SKHY are depositary receipts, but they use opposite unit ratios, and that changes the arithmetic.
| Feature | TSMC ADR (TSM) | SK hynix ADR (SKHY) |
|---|---|---|
| U.S. exchange | NYSE | Nasdaq |
| Home listing | TWSE: 2330 (Taipei, TWD) | KRX: 000660 (Seoul, KRW) |
| ADS ratio | 1 ADR = 5 ordinary shares[2] | 1 ADS = 1/10 ordinary share[3] |
| Depositary bank | Citibank, N.A.[2] | Named in the SK hynix prospectus[3] |
| U.S. listing date | October 8, 1997[4] | July 10, 2026[5] |
| Maturity | ~29 years of trading | Weeks old at the time of writing |
The ratio flips the direction of the multiplier. To compare TSM with 2330.TW you divide the ADR price across five ordinary shares; to compare SKHY with 000660 you scale one ADS up by ten to equal one Korean share. Get this wrong and the premium is off by a factor of fifty, not a rounding error.
The two premium formulas side by side
Because the ratios differ, the parity calculation looks different even though the logic is identical: convert both legs to the same currency and the same ownership unit, then compare.
SKHY premium (USD/KRW quoted as won per dollar):[6]
SKHY premium = SKHY close ÷ parity per ADS − 1
TSM premium (USD/TWD quoted as NT dollars per dollar):
TSM premium = implied TWD per share ÷ 2330.TW close − 1
In both cases the premium is a ratio of two independently observed prices at a chosen moment. It is not a quote for a trade you can execute, and it does not say which leg is "correct."
A worked TSMC example, using a verified historical close
To make the TSM arithmetic concrete, take a single verified observation: TSM closed at $237.56 on July 16, 2025.[7] The premium calculation needs the matching 2330.TW close and the USD/TWD rate for that date. Rather than present an unverified single-day Taipei close as if it were precise, we anchor on a figure Bloomberg compiled for the same month: TSM traded at an average premium of about 24% over its Taipei listing in July 2025.[8]
Working backwards from that monthly average shows what the inputs imply:
TSM close (verified): $237.56 on July 16, 2025[7]
July 2025 average premium (verified): ≈ 24%[8]
Implied parity value of one TSM ADR at a 24% premium:
≈ +24% (July 2025 monthly average)
In other words, one TSM ADR changed hands for roughly 24% more than the currency-adjusted value of the five Taipei ordinary shares it represents, averaged across July 2025. This is a monthly-average illustration anchored on one verified daily ADR close, not a same-instant executable quote.
What a 28-year history reveals that a debut cannot
The most useful thing TSM offers SKHY readers is a long record. Bloomberg-compiled data put TSM's average premium over the prior decade at about 7.4%, before the spread widened sharply in the AI-driven demand surge of 2024-2025.[8] Within that surge the premium moved a lot: roughly 30% in February 2024, an average near 17% in the second quarter of 2024, about 17% in April 2025, and about 24% in July 2025.[8][9] By August 2025 the monthly spread was the widest since April 2009.[8]
Two longer-horizon reference points are worth noting. Economist Owen Lamont, writing for Acadian Asset Management, put the TSM premium near 80% during the 2000 dot-com bubble and near 20% during the 2021 rally.[10] And by October 2025 the premium had reached its highest level since 2002 on a 50-day moving-average basis.[11] The common thread is that even a mature, highly liquid ADR does not sit at a single "normal" premium — it occupies a range that widens and compresses with U.S. demand, home-market sentiment, and currency.
The benchmark for SKHY: a 29-year-old ADR with deep two-way liquidity still saw its premium swing from roughly 7% to 30% inside a single year. SKHY's 15.8-51.1% debut range is therefore wide, but it is not a different species of number — it is the same phenomenon observed during the most volatile window a listing ever has, before supply, conversion, and arbitrage have had time to work.
Why both premiums exist, and why neither is free money
If a depositary receipt simply represented the same shares, the premium should collapse to zero. It does not, for the same structural reasons in both Taipei-Seoul and New York:
- Non-overlapping hours. NYSE and TWSE, like Nasdaq and KRX, trade in different time zones. A New York quote is frequently compared with an already-closed home-market price, so news reprices one side while the other is shut.
- Conversion friction. Issuing or cancelling depositary shares runs through the depositary bank, settlement, fees, and operational timing.[3] That friction is real even when the spread looks large.
- Costs and access. Spreads, taxes, stock-borrow availability, short-sale rules, and different investor access mean the two legs cannot always be executed at the displayed size or price. Our premium-explainer covers these constraints in depth.
- Different investor bases. U.S. retail and index-driven demand can bid for the ADR even when the home-market share is flat, and vice versa. In 2024-2025, strong U.S. appetite for AI-chip exposure was widely cited as a driver of TSM's widening premium.[9]
The mechanics that prevent instant convergence are why both a 7% and a 50% premium can be "real" observations rather than errors. They are also why a displayed premium is an informational comparison, not an executable return.
Reading SKHY through the TSMC lens
Three practical lessons carry from the older ADR to the newer one.
1. Treat the debut window as price discovery, not equilibrium
TSM's premium has had nearly three decades to find a range and still moves by tens of percentage points. SKHY's first-two-weeks range reflects IPO allocation turnover, launch publicity, a Korean market holiday, and unusually large price moves — the conditions least like a steady state.[1] The honest baseline is "wide and volatile," not a number.
2. Watch which leg is driving the spread
A premium can widen because the ADR rallies, the home share falls, the home currency weakens, or a combination. During SKHY's debut the U.S. and Korean legs frequently moved at very different speeds on the same day.[1] The same decomposition applies to TSM: a wider premium does not by itself tell you the ADR is "expensive" — it tells you the two prices diverged, and you need to look at both to see why.
3. Compare matched closes, not just live quotes
A live premium often pairs a current U.S. quote with an already-closed home market. That is useful, but it mixes information sets. For trend, wait for same-calendar-date closes on both sides. The premium history page lets you test whether SKHY's early ranges persist, compress, or change character over time — the same discipline a TSM watcher would apply.
Bottom line
TSMC and SK hynix ADRs share a structure — a U.S. depositary share over an Asia-listed ordinary — but sit at opposite ends of the maturity curve. TSM's near-three-decade record shows that even a deep, liquid ADR carries a premium that ranges from single digits to roughly 30% depending on the cycle, and that widened to historic extremes in 2024-2025. SKHY's 15.8-51.1% debut range is the same phenomenon observed during the most volatile window any listing experiences. The right way to use TSM as a benchmark is not to copy its average, but to copy the question it answers: what is the home-market value, what is the currency, what is the ratio, and which leg moved?
References
- SKHY Premium, SKHY ADR: The First Two Weeks — Premium Patterns, Volume & What to Watch, July 27, 2026. Matched-close premium table for the first 11 Nasdaq sessions.
- Taiwan Semiconductor Manufacturing Company Ltd., Form F-3 Registration Statement, SEC EDGAR. "Each American depositary share represents five common shares"; "Citibank, N.A. is the depositary bank for the ADSs."
- SK hynix Inc., Final Prospectus, July 9, 2026. Cover page: one-tenth-share ADS ratio, $149 offer price, 177.9 million ADS offering, and depositary arrangements.
- TSMC Investor Relations, Frequently Asked Questions: TSMC's ADS were listed on the NYSE under "TSM" on October 8, 1997.
- Nasdaq Newsroom, Global Innovation Meets Global Capital: SK hynix Lists on Nasdaq, July 10, 2026.
- SKHY Premium, SKHY Premium Methodology: parity per ADS = 000660 close ÷ USD/KRW ÷ 10; premium = SKHY ÷ parity − 1.
- Yahoo Finance, TSM Historical Prices, July 16, 2025 close of $237.56, accessed August 2026.
- Bloomberg, TSMC Stock Price Dislocation Reaches Widest Level in 16 Years, Charlotte Yang, August 1, 2025. Decade-average premium ~7.4%; ~24% in July 2025; ~17% in April 2025; widest monthly spread since April 2009.
- Bloomberg, A Popular Arbitrage Trade Backfires as TSMC Frenzy Grows in US, June 17, 2024. Premium ~30% in February 2024 and ~17% Q2-2024 average (also mirrored via Yahoo Finance republication).
- Acadian Asset Management, Owen A. Lamont PhD, TSMC: Totally Stupid Market Chaos, October 2024. Premium near 80% in 2000 and near 20% in 2021.
- The Business Times (Singapore), TSMC ADR premium tops two-decade high as global buyers pile in, October 16, 2025. Highest premium since 2002 on a 50-day moving-average basis.