The semiconductor index climbed 82% across the first 100 trading days of 2026 — its best-ever performance over that window — with chipmaker equities broadly up roughly 70% through the first half of the year, according to Reuters.

The rally was broad-based from the outset. ASML, Intel, and Micron Technology were among the early leaders when chipmaking stocks surged in the opening sessions of January, per CNBC. Micron has since become the headline performer: the memory specialist is up 871.76% on a one-year return basis as of June 2026, according to NerdWallet. That figure reflects the decisive shift in memory pricing and volume as AI training and inference workloads push HBM and DDR5 demand well beyond prior cycle peaks.

Earnings across the sector have validated the price action. Samsung reported Q1 2026 operating profit of 57.2 trillion won — an eightfold year-on-year increase — with its semiconductor division alone generating 81.7 trillion won in revenue, CNBC reported. The company reached a $1 trillion market capitalisation in 2026, and its shares surged more than 15% on May 6 following the earnings release. Samsung and SK Hynix together now account for 55% of South Korea's benchmark stock index, according to Yahoo Finance, a concentration that makes the KOSPI effectively a proxy for AI memory demand.

TSMC's numbers are similarly outsized. The foundry posted a 58% profit surge in 2026, driven by AI accelerator tape-outs from its major hyperscaler and fabless customers, Bloomberg reported. TSMC held 72% foundry market share as of Q1 2026, and occupies 41.5% of Taiwan's TAIEX index — meaning a geopolitical shock to the strait registers simultaneously as a supply chain event and a market-cap event for the entire Taiwanese equity market. ASML, the sole supplier of EUV lithography equipment, responded to demand visibility by lifting its 2026 revenue forecast to a range of 36–40 billion euros, Reuters reported. The upward revision signals that leading-edge capacity additions — at TSMC, Samsung, and Intel Foundry — are proceeding faster than ASML's prior guidance assumed.

As of late June 2026, global equities were still being lifted by chipmaker earnings strength, with the dollar near a one-year high, Reuters noted.

The concentration risk embedded in these moves is worth examining directly. When a single company (TSMC) accounts for nearly three-quarters of global leading-edge foundry capacity and more than two-fifths of its home country's benchmark index, and when Samsung and Hynix together own the majority weighting in another, national equity markets have become structurally coupled to the capital expenditure cycles of a handful of U.S. hyperscalers. A slowdown in AI infrastructure spending — whether from macro headwinds, a hyperscaler earnings miss, or a regulatory intervention — would transmit through chipmaker P&Ls directly into the index values of two of Asia's largest economies. The WSJ has noted that the sector had added $5.7 trillion in market capitalisation through late May, raising the natural question of how much forward demand is already priced.

That question has no clean answer yet. Capital expenditure commitments from the major cloud providers remain on record trajectories for 2026 and into 2027, and ASML's revised guidance suggests equipment lead times are not yet compressing. But 70–80% equity returns in a single half-year rarely leave much margin for disappointment. The sector is pricing in a prolonged AI buildout; any evidence that the buildout is front-loaded — data centres built ahead of monetisable workloads, or inference efficiency gains reducing the chip-per-query count — would be absorbed quickly and sharply.