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 20, 20264 min read

Memory Paid for the Security Drawdown. I Traded Nothing.

A split session inside the book: two memory positions covered most of what four security-software names took away, and not one of the decliners produced a company-specific reason.

Net impact −$108 −108.23%
Higher 9/32 +0.00%
Micron $974.33 +3.97%
SanDisk $1,600.62 +2.02%
CrowdStrike $190.34 −5.60%
Palo Alto $349.56 −2.84%

A rotation inside the book rather than a move in either direction: memory added, security took it back, and the net was $108 against me on a day the S&P fell 0.84%. 9 of 32 positions closed higher. No trades.

Net book impact −$108 Share counts × the change in each close
Positions higher 9 of 32 A genuinely split session
Best position +$74 Micron, +3.97%
Worst position −$51 Palo Alto Networks, −2.84%

01Where the money went

Figure 1 · Dollar attribution

Two memory positions paid for most of a security-software drawdown

+$74 MU +$64 SNDK +$22 TEM −$23 CRWD −$25 NBIL −$33 EL −$45 SPCX −$51 PANW −$91 Other −$108 NET
Share counts multiplied by the change in each position’s closing price, August 19 to August 20, 2026. Positions moving less than $20 are grouped. Source: Massive Market Data; share counts from this site’s holdings file.

Percentages and dollars point in different directions again, which is the reason I keep drawing this chart rather than reading a decliner list. CrowdStrike fell 5.60% — the largest percentage decline in the book — and cost $23. Palo Alto fell less than half as much in percentage terms and cost more, because it is the larger position.

02What actually happened

Micron rose 3.97% and SanDisk 2.02%, extending the memory bid without any new dated catalyst — the reshoring reports were three days old at that point. Marvell added 5.79%. On the other side, CrowdStrike fell 5.60%, Palo Alto 2.84%, and Fortinet 1.35%, none of them with a company-specific reason I could source. Full session in today’s News writeup.

Positions moving more than $10 · August 20, 2026
PositionCloseDayBook impactvs cost
Micron Technology MU$974.33+3.97%+$74+199%
Sandisk Corp SNDK$1,600.62+2.02%+$64+231%
Tempus AI Inc TEM$66.65+8.82%+$22+34%
ServiceNow Inc NOW$129.75+2.00%+$15+53%
Advanced Micro Devices AMD$469.45+0.65%+$15+136%
Vertiv Holdings Co VRT$264.63+1.39%+$11−13%
Invesco QQQ Trust QQQ$710.93−0.72%−$10+27%
Alphabet Inc GOOGL$340.67−1.17%−$12+24%
Talen Energy Corporation TLN$316.99−1.66%−$16+1%
Vanguard S&P 500 ETF VOO$701.01−0.83%−$18+21%
SPDR S&P 500 ETF SPY$762.60−0.84%−$19+16%
CrowdStrike Holdings CRWD$190.34−5.60%−$23+101%
GraniteShares 2x Long NBIS Daily ETF NBIL$24.41−3.29%−$25+164%
Estée Lauder Companies EL$96.15−1.90%−$33+39%
Space Exploration Technologies (SpaceX) SPCX$134.00−4.05%−$45−1%
Palo Alto Networks PANW$349.56−2.84%−$51+118%

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.