S&P 500 rises 1.14% as chipmakers lead the rebound from the Fed hike
S&P 500 close: 7,637.76 (+1.14%) Breadth: Nasdaq +1.69%, Dow +0.61%, Russell 2000 +0.55% Sentiment: bullish
The S&P 500 closed at 7,637.76 on 17 September 2026, up 85.95 points or 1.14%, as semiconductors recovered the ground lost to the prior day's Federal Reserve rate hike and the 10-year Treasury yield slipped back below 5%. Generac GNRC.US gained 18.34% to $207.23 after Amazon contracted it to supply backup generators for data centers, about $2.4 billion of deliveries scheduled across 2027 and 2028. The VIX fell 12.82% to 15.44, unwinding Wednesday's post-decision spike.
What moved the index
- Semiconductors: the SOXX chip ETF rose 3.39% and SMH 2.76%, worth roughly 41 bps of the 114 bps index move at about a 12% S&P weight. Arm ARM.US added 8.57%, United Microelectronics UMC.US 8.61%, Astera Labs ALAB.US 9.06%, AMD AMD.US 6.36% and Micron MU.US 5.50% to $977.50. The 10-year yield at 4.95%, down 1.18% and lower for the first time in nine sessions, let buyers pay up for long-duration earnings again.
- Rest of technology: XLK closed +2.25%, and with semiconductors stripped out the remainder of the sector contributed about 38 bps. Oracle ORCL.US rose 5.19%, Microsoft MSFT.US 1.52% and Apple AAPL.US 1.38%.
- Consumer discretionary: XLY +1.10% at roughly an 11% weight added about 12 bps. Tesla TSLA.US gained 2.27% and Amazon AMZN.US 2.13%.
- Communication services: XLC fell 0.58%, subtracting about 6 bps. T-Mobile TMUS.US dropped 5.57% to $166.45, Paramount Skydance PSKY.US 4.63% and Netflix NFLX.US 1.44%.
Together these account for about 85 of the 114 bps index move. The residual sits in health care (XLV +0.62%), energy (XLE +0.70%) and materials (XLB +0.69%), with financials the only other negative sector at XLF -0.09%.
Session highlights
- GNRC.US +18.34% to $207.23 on the Amazon data-center generator award: about $2.4 billion of 2027 and 2028 deliveries, up to $8 billion of potential volume tied to warrant vesting, and a right for Amazon to buy $320 million of Generac stock.
- VICR.US +17.66% to $216.39 after Vicor licensed its Vertical Power Delivery patents to an unnamed OEM for AI and networking processors, following a New Hampshire fab expansion announced 11 September and a $150 million buyback authorization.
- Nuclear and grid-power names ran on the same data-center demand. XE.US +12.08%, INIO.US +12.03%, OKLO.US +11.31%, SMR.US +8.92%, ETN.US +2.93% and VST.US +2.26%.
- TEM.US +14.85% to $80.36, extending a week-long run after a 15 September Morgan Stanley note put $330 million to $400 million of annual revenue in play from xT and xF diagnostic reimbursement pricing.
- DKNG.US -7.64% to $22.47, with FLUT.US -5.19%, SRAD.US -6.58% and SGHC.US -3.83%, as investors repriced sportsbook competitive position against prediction markets.
Sector scorecard
- Best: Technology XLK (+2.25%), where semiconductors SOXX (+3.39%) did the work
- Worst: Communication Services XLC (-0.58%)
- Dispersion (best minus worst): 2.83 pts
- Nine of eleven sectors closed higher. Communication services showed the widest internal spread: TMUS.US fell 5.57% while the sector itself lost only 0.58%.
Top movers
| Ticker | Move | Reason |
|---|---|---|
| GNRC.US | +18.34% | Amazon data-center generator deal, $2.4b 2027 to 2028 |
| VICR.US | +17.66% | Vertical Power Delivery license to an unnamed AI OEM |
| TEM.US | +14.85% | Morgan Stanley lifted diagnostic reimbursement revenue outlook |
| PURR.US | +12.15% | Unannounced, likely flow-driven. |
| XE.US | +12.08% | Nuclear name bid on data-center power demand |
| AN.US | -10.49% | Cautious Morgan Stanley conference commentary; 52-week low |
| MTZ.US | -7.92% | Zacks cut to Sell on communications-segment margin guidance |
| DKNG.US | -7.64% | Prediction-market competition repriced against sportsbooks |
| XRAY.US | -7.54% | Unannounced, likely flow-driven. |
| TTAN.US | -7.53% | Unannounced, likely flow-driven. |
Notable announcements
- Generac and Amazon: about $2.4 billion of generator deliveries across 2027 and 2028, up to $8 billion tied to warrants, plus a $320 million stock purchase right.
- Vicor: non-exclusive Vertical Power Delivery license to an unnamed OEM, on top of the $150 million buyback authorized 11 September.
- FLNC.US -15.36% to $7.66 after Fluence cut FY26 revenue guidance to $2.4 billion from $2.9 billion to $3.1 billion.
- RARE.US +12.58% to $14.50 on FDA approval of its gene therapy for Sanfilippo syndrome type A.
After the bell
No S&P 500 company reported after the 17 September close. Lennar LEN.US, which posted fiscal Q3 the prior evening at $1.23 adjusted EPS against $1.30 expected and cut full-year deliveries to 80,000 to 81,000 homes from 82,000 to 83,000, finished the session up 1.71% at $79.70.
Next session catalysts (ET)
- Fri 09:30: cash open. S&P futures ES=F last 7,702.25 (+1.04%), Nasdaq futures NQ=F 29,720.50 (+1.59%)
- Fri 16:00: quarterly index option and futures expiry, the third Friday of September and typically the heaviest volume session of the quarter
- Fri: Fed speakers resume after the FOMC blackout, with 16 of 18 officials projecting at least one further hike before year-end
- Ongoing: WTI at $101.09 (-1.31%) and gold at $4,380.60/oz (-0.16%) as Saudi Arabia restores East-West pipeline capacity
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