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%

Interim NoteAugust 24, 20265 min read

The Worst Session of the Month. And Still No Trade.

Two memory positions were more than half the damage, not one large decliner produced company news, and the session found a gap in my written rules rather than a reason to transact.

Net impact −$658 −657.59%
Higher 7/32 +0.00%
SanDisk $1493.12 −6.45%
Micron $910.43 −5.83%
Meta $559.02 +1.66%
Tempus AI $66.17 −8.97%

The worst single session this book has had since I started writing these notes: $658 against me, 7 of 32 positions higher, and the damage concentrated almost entirely in the names with the least earnings behind them. No trades.

Net book impact −$658 Share counts × the change in each close
Positions higher 7 of 32 The narrowest breadth of the month
Worst position −$206 SanDisk, −6.45%
Best position +$42 Meta Platforms, +1.66%

01Where the money went

Figure 1 · Dollar attribution

Two memory positions were more than half the day’s damage

+$42 META +$39 EL −$26 TEM −$27 TLN −$30 DDOG −$35 PANW −$39 INTC −$54 NBIL −$83 AMD −$113 MU −$206 SNDK −$127 Other −$658 NET
Share counts multiplied by the change in each position’s closing price, August 21 to August 24, 2026. Positions moving less than $25 are grouped. Source: Massive Market Data; share counts from this site’s holdings file.

SanDisk and Micron together cost $319 of the $658 total. That is the concentration risk in this book showing up exactly as the July letter said it would — not as a single position blowing up, but as two positions in the same theme moving together on the same day.

02How much cushion is left

“Still ahead of cost” is easy to say. Here it is sized: how far each of the day’s big movers would have to fall from Monday’s close to reach what I actually paid.

Distance to my cost basis · August 24, 2026 close
PositionCloseMy costFall to reach costvs cost
Sandisk Corp SNDK$1,493.12$483.21−67.6%+209%
Micron Technology MU$910.43$325.83−64.2%+179%
GraniteShares 2x Long NBIS Daily ETF NBIL$22.34$9.23−58.7%+142%
Rocket Lab USA RKLB$68.28$78.59+15.1%−13%
Tempus AI Inc TEM$66.17$49.73−24.8%+33%
Vertiv Holdings Co VRT$254.97$304.90+19.6%−16%

Vertiv is the only one already below water, and it went there before this week. The rest have a lot of room, which is the honest reason a session like Monday reads as a bad day rather than a problem — it is cushion earned earlier, not judgement exercised now.

03The full session

Positions moving more than $10 · August 24, 2026
PositionCloseDayBook impactvs cost
Meta Platforms META$559.02+1.66%+$42+139%
Estée Lauder Companies EL$104.13+2.15%+$39+51%
The Cheesecake Factory CAKE$114.61+1.13%+$10+152%
Symbotic Inc SYM$40.03−4.30%−$13+4%
Rocket Lab USA RKLB$68.28−5.91%−$13−13%
Broadcom Inc AVGO$358.76−2.63%−$13+22%
Invesco QQQ Trust QQQ$706.32−1.00%−$14+27%
Space Exploration Technologies (SpaceX) SPCX$135.00−1.44%−$16+0%
Nebius Group N.V. NBIS$210.91−3.75%−$16+134%
Vertiv Holdings Co VRT$254.97−2.66%−$21−16%
Tempus AI Inc TEM$66.17−8.97%−$26+33%
Talen Energy Corporation TLN$305.54−2.84%−$27−3%
Datadog Inc DDOG$225.77−4.18%−$30+89%
Palo Alto Networks PANW$350.90−1.95%−$35+119%
Intel Corporation INTC$87.26−3.12%−$39+133%
GraniteShares 2x Long NBIS Daily ETF NBIL$22.34−7.49%−$54+142%
Advanced Micro Devices AMD$456.75−3.49%−$83+129%
Micron Technology MU$910.43−5.83%−$113+179%
Sandisk Corp SNDK$1,493.12−6.45%−$206+209%

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.