Market snapshot · September 18, 2026 close
S&P 500 (SPY) $761.69 −0.13% Nasdaq-100 (QQQ) $721.45 +0.60% Dow (DIA) $515.88 −0.48% Russell 2000 (IWM) $284.10 −0.52% 10-Year Treasury (IEF) $90.80 −0.49% Crude Oil (USO) $153.82 −0.93% Gold (GLD) $401.17 +0.74% US Dollar Index (UUP) $28.39 −0.02% Volatility (VXX) $17.76 +0.31% Semiconductors (SMH) $573.00 +2.17% Silver (SLV) $59.93 +1.65% Emerging Markets (EEM) $67.03 +0.19% Bitcoin (BTC) $81,055.00 +4.51% Ethereum (ETH) $2,630.20 +5.92% S&P 500 (SPY) $761.69 −0.13% Nasdaq-100 (QQQ) $721.45 +0.60% Dow (DIA) $515.88 −0.48% Russell 2000 (IWM) $284.10 −0.52% 10-Year Treasury (IEF) $90.80 −0.49% Crude Oil (USO) $153.82 −0.93% Gold (GLD) $401.17 +0.74% US Dollar Index (UUP) $28.39 −0.02% Volatility (VXX) $17.76 +0.31% Semiconductors (SMH) $573.00 +2.17% Silver (SLV) $59.93 +1.65% Emerging Markets (EEM) $67.03 +0.19% Bitcoin (BTC) $81,055.00 +4.51% Ethereum (ETH) $2,630.20 +5.92%

August 2026 · Interim Note

Twenty-Four of 32 Positions Fell Friday. Tempus AI Alone Was a Third of the Damage.

August 28, 2026 · Not a full monthly letter — a short check-in between them

A quiet reading room with wooden tables, lamps, and shelves of books
Friday’s book: a broad decliner, not a single-name story — 24 of 32 positions closed lower.

The S&P 500 fell 0.23% Friday, which understates what happened underneath it. NBIL (−$60.60), Palo Alto Networks (−$56.30) and AMD (−$55.45) led the drag, against ServiceNow (+$37.68) and Meta (+$32.04) pulling the other way. Net impact: −$430.79. 24 of 32 positions closed lower. No trades.

−$430.79Net book impact, August 28 close vs. August 27
−$60.60NBIL alone, the day’s largest single drag
+$37.68ServiceNow, the day’s largest single gain
24 of 32Positions lower on the day

Where the $431 came from

Figure 1 · Cumulative dollar attribution

Two winners covered less than a fifth of what ten losers took away

+$38 NOW +$32 META −$61 NBIL −$56 PANW −$55 AMD −$51 EL −$37 INTC −$37 VRT −$32 ARM −$27 TEM −$145 Other 22 −$431 NET

Share counts × the change in each position’s closing price, August 27 to August 28, 2026. The eight largest single-name movers are shown individually; the remaining 22 positions are bucketed as “Other 22” and net to −$145.20. Source: Massive Market Data closes, applied to my own share counts.

This is a wide, shallow session rather than a single-name story: 24 of 32 positions fell, but no individual loss beyond NBIL cleared $60. Palo Alto Networks fell 2.94% to $371.59 and AMD fell 2.33% to $465.58 — both continuing the pattern from three sessions ago, where I logged Palo Alto Networks weakness with no dated headline attached. Today’s News article covers the mechanism: a Fed speech that initially lifted the tape, then reversed into a selective selloff of the market’s highest-multiple names.

Positions moving more than $15 · August 28, 2026 close
PositionCloseDayBook impactvs. my cost
ServiceNow (NOW)$144.71+4.54%+$37.68+70.72%
Meta Platforms (META)$578.02+1.21%+$32.04+146.72%
GraniteShares 2x Nebius (NBIL)$21.75−8.50%−$60.60+135.65%
Palo Alto Networks (PANW)$371.59−2.94%−$56.30+131.75%
AMD$465.58−2.33%−$55.45+133.55%
Estée Lauder (EL)$103.39−2.66%−$50.76+49.61%
Intel (INTC)$89.47−2.85%−$36.68+139.06%
Vertiv (VRT)$257.08−4.53%−$36.60−15.71%
Arm Holdings (ARM)$239.05−6.33%−$32.32+15.02%
Tempus AI (TEM)$64.04−9.41%−$26.60+28.79%
Talen Energy (TLN)$296.11−2.78%−$25.42−5.87%

The position I keep coming back to

Tempus AI (TEM) daily close vs. SPY, indexed, last 46 trading sessions through August 28, 2026. Source: Massive Market Data.

Tempus AI fell 9.41% to $64.04 Friday, the worst single-name move in the book by dollar and percentage after NBIL. I don’t have a dated headline for the drop — the position rallied more than 75% earlier this month on the Merck-Moderna cancer-vaccine trial result tied to its pending Personalis acquisition, and Friday looks like some of that giving back rather than new bad news. My 4-share position is still up 28.79% against cost even after Friday, which is the right way to hold this one in perspective: a single loud week either direction doesn’t change what I know about the business, and I haven’t traded it in either direction.

NBIL, my 30-share position in GraniteShares’ 2x leveraged Nebius fund, fell 8.50% — almost exactly double NBIS’s own 4.26% decline, the fund doing what it says on the label in the direction I like least. I’ve written before about what “2x daily” means in dollars; today is the mirror image of the up day I wrote that piece about, and the arithmetic runs the same way in reverse.

No trades today

The Blackout Rule and Holding Period exist for exactly this kind of session. Nothing here is new information about any company’s fundamentals — it reads, per today’s News article, as a rate-sensitive reversal hitting the market’s highest-multiple names broadly, which includes several names I hold for reasons unrelated to Friday’s price action. I made no trades.

Sources cited in full on the linked News article. Prices via Massive Market Data; dollar impacts computed from my own share counts. This note is educational and reflects my personal views only. It is not investment advice.