US Markets Overnight: Micron crashes the trillion-dollar club while the Mag 7 watches from the cheap seats

US Markets Overnight welcomed company #8 to the Mag 7

Some sessions belong to the giants. This one belonged to the memory guys. While you were asleep, the US session of Tuesday 26 May 2026 served up one of the stranger set-ups of the year: the Nasdaq and the S&P 500 both punched out fresh record closes, the Dow went the other way, and the actual headline act wasn’t any of the Magnificent 7 but Micron Technology (NSDQ:MU), which gatecrashed the trillion-dollar club after a broker decided its shares were worth roughly three times what it had been saying a week earlier. The stock jumped more than 19% (!), which means it is now worth more than US$1 trillion.

Wall Street came back from the Memorial Day long weekend with a spring in its step, helped along by hopes of a US-Iran deal that might finally take some heat out of the oil price. The result was a tale of two tapes, and a reminder that “tech rallied” and “the Mag 7 rallied” are no longer the same sentence.

The scoreboard: green up top, red down the bottom, oil doing the splits

The S&P 500 closed at 7,519.12, up 0.6% and a record. The Nasdaq Composite did the heavy lifting, climbing 1.2% to 26,656.18, also a record, dragged higher almost single-handedly by semiconductors. The Dow Jones Industrial Average was the odd one out, slipping 0.2% to 50,461.68 as oil-sensitive and industrial names weighed on the price-weighted index. The small-cap Russell 2000 was the quiet star, jumping around 1.7% to close above 2,900 for the first time in its life, a milestone that says more about broadening risk appetite than any single stock.

Over in assets, WTI crude eased about 2.4% to roughly US$94 a barrel as traders priced in the chance of a diplomatic off-ramp in the Middle East, though Brent stayed stubbornly bid near US$97, a divergence worth keeping an eye on. Gold drifted about 0.3% lower to around US$4,540 an ounce, with rate-hike chatter doing the bullion no favours. Bitcoin was broadly flat, hovering near US$77,000. The US 10-year Treasury yield fell about eight basis points to 4.50%, a touch of relief for duration. The VIX ticked up around 1.5% to roughly 16.8, which is the market equivalent of a raised eyebrow rather than a scream.

The Magnificent 7: present, but not the story

Here’s the twist. On a day the headlines screamed “tech leads markets to records”, the Mag 7 was a study in mediocrity. The honest framing is that US markets overnight rallied despite the seven, not because of them.

Alphabet was the standout of the bunch, closing at US$385, up 1.4%. The Google parent has been on an extraordinary run, and the latest fuel is its tie-up with Blackstone to build out data centres dedicated to its in-house TPU chips, a move that quietly chips away at Nvidia’s pricing power while giving Alphabet another guaranteed buyer for its own silicon. Investors clearly like a company that sells the picks, the shovels, and the gold mine. Tesla was the other genuine winner, up 1.8% to US$434, riding momentum and the general risk-on mood rather than anything company-specific. Meta nudged up 0.3% to US$612, which barely registers.

The rest were a wall of mild red. Apple slipped 0.2% to US$308, Amazon eased 0.4% to US$265, and Microsoft was the laggard, down 0.6% to US$416. Most telling of all was Nvidia, which actually fell 0.2% to US$215 on a day its own sector was on fire. That is the single most important detail in the whole session: the great chip rally happened around Nvidia, not through it. The market is no longer treating AI semis as one monolithic trade where Jensen’s boat lifts all others. Punters are getting selective, and on this particular day, they were shopping elsewhere.

Chip check: the foundry boys had a feeling, the memory boys had a party

If the Mag 7 was the support act in US markets overnight, the semiconductor complex was the main event, and Micron was the frontman. Shares of the memory maker rocketed roughly 19% to vault past a US$1 trillion market capitalisation for the first time, joining a club that until recently felt reserved for a handful of names. The catalyst was a genuinely audacious call from UBS analyst Timothy Arcuri, who jacked his price target to a street-high US$1,625 from US$535, an upgrade so large it implies a near-doubling of the company’s value from here.

The thesis, laid out in the broker’s note, is that long-term supply agreements and sold-out high-bandwidth memory have turned Micron from a boom-bust commodity play into something closer to AI infrastructure. Whether that re-rating is visionary or vertigo-inducing is the debate of the week, and not everyone is convinced a tripled target on a single morning is the act of a sober mind.

Around Micron, the rest of the semiconductor sector was a mixed bag rather than a uniform melt-up. AMD pushed higher as the selective AI-chip trade kept rotating in its favour, while Intel went the other way, drifting toward US$118 and shedding ground after a fresh broker downgrade questioned its data-centre spending into 2027.

The contrast captures the sector’s new mood perfectly: this is no longer a “buy everything with silicon in it” market. The SOX semiconductor index notched a fresh record on Micron’s coattails, but underneath the index, capital is being shoved from name to name on specific catalysts. The AI capex tailwind is still blowing hard, but it’s no longer blowing evenly.

One thing worth watching

Keep one eye firmly on the Strait of Hormuz. The whole risk-on tone of US markets overnight leaned on hopes of a US-Iran de-escalation, and that is exactly the kind of optimism that can reverse on a single headline. With WTI and Brent already disagreeing about how the story ends, any sign the talks are stalling, or any fresh flare-up in the Gulf, would send oil higher, reignite the inflation-and-higher-for-longer narrative, and put the Treasury market straight back on edge.

For Australian investors, watch the energy complex and the 10-year yield at the open: if crude spikes and yields climb, the chip euphoria that powered US markets overnight could cool faster than you can say “memory super-cycle”. For more on how the AI-chip frenzy is reshaping the leaderboard, see our take on the changing of the AI guard.