S&P 500 adds 0.17% as semiconductors offset nine falling sectors
S&P 500 close: 7,650.50 (+0.17%) Breadth: Nasdaq +0.39%, Dow -0.18%, Russell 2000 -0.50% Sentiment: mixed
The S&P 500 closed at 7,650.50 on 18 September 2026, up 12.74 points or 0.17%, as a 2.78% gain in the PHLX Semiconductor index offset declines in nine of the eleven sectors. MicroStrategy MSTR.US rose 16.39% to $153.92 after B. Riley, Canaccord and Barclays lifted price targets and bitcoin gained 6.37% to US$81,170. The 10-year Treasury yield added 5 basis points to 4.998%, leaving utilities, real estate and materials each about 1.4% lower.
What moved the index
- Semiconductors: the PHLX Semiconductor index rose 2.78% and the VanEck Semiconductor ETF SMH.US 2.21%, worth roughly 26 bps of the 17 bps index move at about a 13% S&P weight. Micron MU.US added 3.92% to $1,015.80, Broadcom AVGO.US 2.97%, Advanced Micro Devices AMD.US 2.70% and Nvidia NVDA.US 1.34%.
- Industrials and large-cap internet: XLI closed +0.44% for about 4 bps, with Amazon AMZN.US +1.00% and Alphabet GOOGL.US +0.64% adding roughly 7 bps between them.
- Communication services and software: XLC fell 1.37% and subtracted about 18 bps together with the software names. Netflix NFLX.US dropped 4.67% to $71.79 after a Wells Fargo downgrade, Meta META.US 2.43%, Oracle ORCL.US 1.98% and Microsoft MSFT.US 0.80%.
- Rate-sensitive sectors: XLU and XLB both closed -1.42% and XLRE -0.95%, about 7 bps of drag, as the 10-year yield returned to 4.998% after Thursday's dip below 5%.
Together these account for about 12 of the 17 bps index move. The residual sits in health care (XLV -0.25%) and financials (XLF -0.04%), where the moves were small enough to roughly cancel.
Session highlights
- Bitcoin rose 6.37% to US$81,170. Crypto-linked equities posted the session's largest gains: BTDR.US +15.39%, MARA.US +13.75%, COIN.US +11.66%, HOOD.US +9.12%, RIOT.US +8.55% and CLSK.US +8.39%. About US$238 million of bitcoin short positions were liquidated as the price cleared US$78,000.
- 18 September was quarterly options and futures expiry, the third Friday of the quarter.
- SMR.US fell 8.52% to $8.27 after UBS cut it to Sell with a $6 target, down from $10. Other nuclear names also fell: OKLO.US -4.16%, LEU.US -3.08% and CCJ.US -1.27%.
- Sportsbook operators fell for a second session on prediction-market competition: RSI.US -7.72%, PENN.US -5.78%, DKNG.US -3.20% and FLUT.US -3.18%.
- Cybersecurity names fell after a week of 8% to 14% gains: OKTA.US -4.03%, CRWD.US -3.28% and PANW.US -3.06%.
- WTI crude fell 1.81% to US$95.47 and Brent 1.16% to US$98.77. Gold added 0.37% to US$4,415.90. The dollar index finished at 100.215, down 0.03%.
- The VIX fell 0.63 points to 14.81, a 4.08% decline that extended Thursday's 12.82% drop from the post-decision spike.
Sector scorecard
- Best: Technology XLK (+0.82%)
- Worst: Materials XLB and Utilities XLU (both -1.42%)
- Dispersion (best minus worst): 2.24 points
- Two sectors closed higher and nine lower. Communication services XLC -1.37% held the widest internal spread, Alphabet GOOGL.US +0.64% against Netflix NFLX.US -4.67%.
Top movers
| Ticker | Move | Reason |
|---|---|---|
| MSTR.US | +16.39% | Three brokers raised targets, bitcoin +6.37% |
| BTDR.US | +15.39% | Bitcoin miner tracking the US$81,170 print |
| MARA.US | +13.75% | Bitcoin miner, moved with RIOT.US +8.55% |
| PS.US | +13.69% | Unannounced, likely flow-driven. |
| COIN.US | +11.66% | Exchange volumes on the bitcoin move |
| XENE.US | -30.69% | Phase 3 depression enrolment paused on safety review |
| SMR.US | -8.52% | UBS cut to Sell, target $6 from $10 |
| RSI.US | -7.72% | Sportsbooks lower again on prediction markets |
| BTU.US | -7.42% | Coal miners lower, AMR.US -5.69% |
| TNGX.US | -7.41% | Unannounced, likely flow-driven. |
After the bell
- No S&P 500 company reported after Friday's close. BlossomHill Therapeutics BLSM.US was the only scheduled Friday reporter, and the next after-market block lands on Tuesday 22 September with KB Home KBH.US and Worthington Enterprises WOR.US.
- Bitcoin held above US$81,000 after the 4:00pm ET equity close, having cleared US$78,000 during the session.
Notable announcements
- Warren Buffett stepped down as chairman of Berkshire Hathaway, a post he had held since 1970. The class B shares closed up 0.11% at $509.77.
- Xenon Pharmaceuticals XENE.US filed a new drug application for focal onset seizures and paused enrolment in its major depressive disorder and bipolar depression studies after reviewing neuropsychiatric adverse events. Deutsche Bank cut the stock to Hold with a $46 target, down from $90.
- UBS downgraded NuScale Power SMR.US to Sell and cut its target to $6 from $10, citing project timelines and cash burn. Pomerantz opened a securities investigation the same day.
- Kansas City Fed president Jeff Schmid said the Fed has work to do on inflation and called this week's 25 basis point increase a step in that direction.
- Apple AAPL.US launched the iPhone 18 Pro at a $100 premium to the prior generation on memory costs, with reported three-week delivery waits. The stock closed down 0.26% at $336.13.
Next session catalysts (ET)
- Mon 21 Sep, 8:30am: Chicago Fed National Activity Index for August
- Tue 22 Sep, 10:00am: Richmond Fed manufacturing index for September
- Tue 22 Sep: AutoZone AZO.US, MillerKnoll MLKN.US and Thor Industries THO.US before the open; KB Home KBH.US and Worthington Enterprises WOR.US after the close
- Wed 23 Sep: S&P Global flash US manufacturing and services PMIs for September
- Thu 24 Sep: weekly jobless claims and August new home sales
- Fri 25 Sep: durable goods orders and the final second-quarter GDP print
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