Taiwan's TAIEX trades at about 18 times one-year forward earnings while South Korea's KOSPI sits at about 5.5 times, according to market estimates reported on October 7, 2026 — a valuation gap that prices a hard judgment on which semiconductor scarcity will outlast the AI cycle.

The verdict is striking because Korea's fundamentals have rarely looked stronger. On October 1, Korea's Ministry of Trade, Industry and Resources reported September exports of US$120.94 billion, up 83.5 percent year over year and the first month above US$120 billion. Semiconductors alone hit US$60.30 billion, up 262.8 percent, with memory at US$54.07 billion. Samsung Electronics guided third-quarter operating profit at ₩107.4 trillion (about US$80.2 billion), nearly nine times the ₩12.17 trillion a year earlier.

Yet KOSPI fell 19.3 percent in the July–September quarter while TAIEX rose 3.9 percent — a 23.3-point gap reported as the widest since the turn of the century. By October 7, TAIEX stood at 49,806.37, up 72.0 percent for the year; KOSPI at 6,803.90, up 61.5 percent but 25.4 percent below its June 22 peak of 9,114.55.

Why do markets discount Korea's record profits?

M&G Investments portfolio manager Vikas Pershad put it plainly: Taiwan's earnings "come from volume," while Korea's "in the near-term, are coming from price." Korea's core strength, memory, has historically been cyclical — capacity additions eventually discipline prices. Taiwan's ecosystem, anchored by leading-edge logic, contract foundry and advanced packaging, creates bottlenecks that erode more slowly.

Test the concentration explanation and it belongs to Korea, not Taiwan. TSMC carried a 41.12 percent weight in TAIEX on September 30, but its 60.0 percent gain from NT$1,550 to NT$2,480 lagged the index's 65.5 percent rise; roughly 10 percent of TAIEX stocks had at least doubled this year against 4.1 percent of KOSPI stocks. Samsung and SK hynix together averaged 52.82 percent of KOSPI in September, per KOFIA, implying by IndraStra Global's proxy estimate that the two chipmakers drove close to four-fifths of the index's 62.3 percent year-to-date gain.

Korea also earns more. In Q2 2026, Samsung posted ₩89.5 trillion and SK hynix ₩60.54 trillion in operating profit (76 percent margin) — about US$59.7 billion and US$40.4 billion at Federal Reserve H.10 rates — versus TSMC's NT$766.6 billion (US$24.3 billion, 60.3 percent margin). The Korean pair added roughly US$90 billion of quarterly operating profit year over year; TSMC added about US$9 billion. The market's skepticism is about durability, not magnitude: Societe Generale strategists expect memory price appreciation to slow before normalizing in 2028 as Chinese competition rises.

Where are the durable bottlenecks?

A modern AI accelerator is a system — logic dies on 3nm or 2nm processes, HBM stacks, and TSMC's CoWoS packaging integrating SoC dies with HBM. TSMC held 73 percent of Counterpoint's pure-play foundry market in Q2 2026. TrendForce described 3nm supply as "a temporary single-supplier dynamic dominated by TSMC" and noted the CoWoS shortage, running since 2023, now extends to equipment, substrates and materials. Counterpoint puts the CoWoS supply-demand gap at about 20 percent in 2026, narrowing to roughly 10 percent in 2027 as TSMC expands capacity by more than 60 percent.

HBM complicates the simple story. SK hynix earned 50 percent of Q2 HBM revenue and Samsung 33 percent — Korean firms control roughly five-sixths of the market. But the bottleneck is mobile: SK hynix held 64 percent a year earlier; Samsung rose from 15 to 33 percent as products qualified. SK hynix has also adopted TSMC's logic process for its HBM4 base die and agreed to optimize integration with CoWoS, shifting value toward Taiwan's packaging layers. Erosion is already under way elsewhere: China's CXMT now holds 10 percent of DRAM revenue, up from 4 percent; Rapidus, backed by about US$15 billion in Japanese state support, plans 2nm production with 17 design partners.

Can Korea defend its multiple?

Korea has a route to the same premium. Samsung aims to place about two-thirds of memory output under long-term contracts, and SK hynix has signed agreements with about ten customers. TrendForce still expects Q4 DRAM contract prices up 10 to 15 percent and NAND up 15 to 20 percent; MOTIR's fixed-price series shows a 16Gb DDR5 chip at US$48.00 in September, up from US$37.50 in May — deceleration, not collapse.

The East Asia Institute concludes both economies' bottleneck status is "most likely" to erode gradually over the next 12 to 18 months, naming silicon photonics and copper interconnects as the next constraints. If those constraints form where qualification is slow and suppliers few, the premium stays in Taipei; if HBM remains binding, Korea's 5.5-times multiple may read less as a verdict than as a discount waiting to close.