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%

Market Wrap · August 31, 2026

Marvell Kept Falling on Its Own Guidance While CrowdStrike Led a Cybersecurity Rally on a Raised Outlook

August 31, 2026 · Indices, Marvell (MRVL), CrowdStrike (CRWD), Sandisk (SNDK), Coinbase (COIN)

An aerial view of Lower Manhattan's financial district and the East River at dusk
A quiet 0.30% index decline covering a session that split cleanly along one line: whose guidance improved and whose didn’t.

The S&P 500 fell 0.30% Monday to $767.05 in a lighter pre-Labor-Day session, with the Nasdaq-100 essentially flat (+0.05%). Underneath that quiet index print, the tape kept relitigating last week’s two biggest guidance stories. Marvell fell another 2.29% to $211.66, extending Friday’s 10.28% post-earnings drop on the same soft margin guide, per a same-day Motley Fool report. CrowdStrike rose 5.77% to $231.00 on a new Falcon IQ product launch layered on top of last week’s raised full-year outlook, and pulled the rest of the security-software group with it: Fortinet rose 2.97% and Palo Alto Networks rose 2.84%. Sandisk rose 5.50% to $1,566.70 and Micron rose 2.77%, both extending the memory-pricing rally this site flagged August 20, while Coinbase rose 5.31% alongside a weekend crypto rebound (Bitcoin +1.14%, Ethereum +2.08%). Uber fell 4.02%, the day’s worst move among names this site tracks, without a dated company-specific headline attached.

Story one · Guidance, still the same complaint −2.29% Marvell, extending Friday’s 10.28% margin-guide selloff
Story two · Guidance, the other direction +5.77% CrowdStrike, on a new product launch atop last week’s raise
Story three · Two unrelated tailwinds +5.50% Sandisk, on continued NAND-pricing strength

A company whose guidance keeps disappointing, a company whose guidance keeps improving, and a memory name riding a pricing cycle that has nothing to do with either — three separate mechanisms sitting under a nearly flat index. Source: Massive Market Data.

The tape’s dispersion, in one chart

Figure 1 · Single-day percent moves, August 31

Every name that fell had a guidance complaint attached; most that rose had a guidance raise or an unrelated tailwind

WYFI +6.59% CRWD +5.77% SNDK +5.50% COIN +5.31% FTNT +2.97% PANW +2.84% MU +2.77% NOW +2.27% GOOGL -2.09% MRVL -2.29% CAKE -2.30% AMZN -2.50% NBIL -2.62% UBER -4.02%

Single-day close-to-close percent moves, August 28 to August 31 close, for 14 of the largest movers among AEA’s 32 holdings and 15 watchlist names. Source: Massive Market Data.

Story one: Marvell’s guidance problem didn’t go away over the weekend

Marvell fell 2.29% to $211.66 Monday, adding to Friday’s 10.28% post-earnings decline. A same-day Motley Fool report (“Why Is Marvell Stock Falling, and is it a Generational Buying Opportunity?”) attributed the continued weakness to the same complaint that drove Friday’s drop: a softer fiscal-2028 guide and timing uncertainty around the scope of Marvell’s custom-chip partnership with Google, despite what the same coverage called “stellar AI bookings.” A separate Fool piece the same week flagged that Broadcom, which reports its own earnings September 2, faces investor questions about the same Marvell–Alphabet custom-silicon relationship — Marvell’s guidance problem and Broadcom’s competitive question are, per that reporting, two sides of the same story. Marvell shares are still up roughly 147% year to date despite the two-session slide, per Motley Fool coverage of the Broadcom setup.

Marvell (MRVL) daily close vs. SPY, indexed, last 45 trading sessions through August 31, 2026. Source: Massive Market Data.

Story two: CrowdStrike led a cybersecurity rally that started before Monday

CrowdStrike rose 5.77% to $231.00. A Zacks “Company News” roundup attributed Monday’s move specifically to the launch of a new Falcon IQ solution and new partnerships, layered on top of last week’s earnings beat: CrowdStrike posted 25.8% year-over-year revenue growth, adjusted EPS up 34%, record net-new ARR of $333 million (up 51%), and raised its fiscal 2027 outlook, per Zacks coverage published the same week. A separate Zacks piece published Monday added that CrowdStrike’s AI Detection and Response (AIDR) business “nearly tripled its annual recurring revenue sequentially” in the same quarter. Sector peers moved with it: Fortinet rose 2.97% and Palo Alto Networks rose 2.84%, continuing a pattern from the prior week when Okta rose 28.6% on its own earnings beat and raised guidance, and SailPoint rallied on “momentum from strong quarterly earnings reports by peers CrowdStrike and Okta,” per Motley Fool coverage from Friday. This is a sector re-rating on raised guidance, running in the opposite direction from Marvell’s.

Today’s biggest movers · among AEA’s 32 holdings and 15 watchlist names
TickerCloseChangeDated catalyst
WhiteFiber (WYFI)$18.92+6.59%No dated headline found — logged unexplained
CrowdStrike (CRWD)$231.00+5.77%New Falcon IQ launch and partnerships, atop last week’s raised outlook
Sandisk (SNDK)$1,566.70+5.50%Zacks Rank #1 upgrade on a 17.1% rise in 60-day consensus earnings estimates
Coinbase (COIN)$188.12+5.31%Tracked a weekend crypto rebound (BTC +1.14%, ETH +2.08%)
Fortinet (FTNT)$170.93+2.97%Sympathy with CrowdStrike/Okta's raised-guidance cybersecurity rally
Palo Alto Networks (PANW)$382.13+2.84%Sympathy with CrowdStrike/Okta's raised-guidance cybersecurity rally
Micron (MU)$958.73+2.77%Continued NAND/DRAM pricing tailwind flagged Aug. 20
GraniteShares 2x Nebius (NBIL)$21.18−2.62%Leveraged pass-through of NBIS's decline (2x by design)
Marvell (MRVL)$211.66−2.29%Continuing Friday's soft-guidance selloff; Google-deal timing uncertainty
Uber (UBER)$75.65−4.02%No dated headline found — logged unexplained

Story three: two tailwinds that had nothing to do with earnings season

Sandisk rose 5.50% to $1,566.70 after Zacks added it to its Rank #1 (Strong Buy) list Monday, citing a 17.1% increase in 60-day consensus earnings estimates — an analyst-estimate revision, not a new company announcement. The move extends a pricing-driven rally this site first flagged August 20: Sandisk’s own fiscal Q4 report showed revenue up 51% sequentially to $8.97 billion with non-GAAP gross margin expanding to 84.6%, and Q1 FY2027 guidance of 83–85% margin, per Zacks coverage of that print. Micron rose 2.77% on the same NAND/DRAM tightness, separately reporting a record 84.9% non-GAAP gross margin in its own most recent quarter with a Q4 target of 86%, per Zacks. Coinbase rose 5.31% to $188.12 alongside a broad weekend crypto rebound — Bitcoin rose 1.14% and Ethereum rose 2.08% from Sunday’s close — with continued bullish commentary in circulation, including CEO Brian Armstrong’s public $400,000-by-2030 Bitcoin price target reported by Motley Fool over the weekend. I found no dated, Coinbase-specific headline for Monday itself; the move reads as a beta play on crypto strength.

Full macro tape

Macro instrument snapshot · August 31, 2026 close vs. August 28 close (crypto vs. August 30 close)
InstrumentCloseChange
S&P 500 (SPY)$767.05−0.30%
Nasdaq-100 (QQQ)$716.76+0.05%
Dow (DIA)$531.57−0.65%
Russell 2000 (IWM)$293.93−0.62%
10-Yr Treasury (IEF)$92.74−0.12%
Crude Oil (USO)$133.70+3.08%
Gold (GLD)$408.42−0.11%
US Dollar (UUP)$28.12−0.21%
Volatility (VXX)$18.00−1.96%
Semiconductors (SMH)$556.63+0.64%
Silver (SLV)$60.13+0.18%
Emerging Mkts (EEM)$67.02−0.18%
Bitcoin (BTC)$78,566.10+1.14%
Ethereum (ETH)$2,467.12+2.08%

Crude oil’s 3.08% rise was the macro tape’s largest single move; I found no dated, Monday-specific oil-supply or demand headline in the sources I checked, so it is logged here without an assigned catalyst. Source: Massive Market Data.

What Marvell’s own margin guidance implies in dollars

Marvell’s Q2 non-GAAP gross margin fell to 58.9% from 59.4% a year earlier on record revenue of $2.739 billion, and management guided Q3 FY2027 margin to a range of 57.5–58.5%, per Motley Fool coverage of the earnings call. Holding revenue flat at Q2’s actual $2,739 million — a simplifying assumption, since the sourced coverage gave a margin range but not a specific Q3 revenue figure — that guided range implies a sequential decline in gross profit dollars even before any revenue growth is counted.

Scenario (revenue held flat at $2,739M)Implied gross profitvs. Q2 actual
Q2 actual, 58.9% margin$1,613.3M
Q3 guide, low end (57.5%)$1,574.9M−$38.3M
Q3 guide, midpoint (58.0%)$1,588.6M−$24.7M
Q3 guide, high end (58.5%)$1,602.3M−$11.0M

Assumptions, stated plainly. This table applies Marvell’s own guided Q3 FY2027 gross-margin range (57.5–58.5%, as reported by The Motley Fool) to Q2’s actual revenue of $2,739 million, held flat, because the sourced coverage did not include a specific Q3 revenue figure I could independently verify. Marvell’s custom AI-chip business — the same one driving the margin guide down — is also its fastest-growing segment, so in practice Q3 revenue is far more likely to be higher than Q2’s than flat, which would raise the absolute gross-profit dollars even as the margin percentage compresses. This is not Marvell’s own guidance restated as a dollar figure; it is AEA’s arithmetic applied to two real, sourced inputs, built to show what the margin guide means in dollars rather than only as a percentage.

Elsewhere on the tape

WhiteFiber rose 6.59% and Uber fell 4.02%, both without a dated company-specific headline in the sources checked. Amazon fell 2.50% and Alphabet fell 2.09% — both mentioned Monday in a Motley Fool piece on Appaloosa Management’s David Tepper exiting his Sandisk position in Q2 2026 after a “3,000%” rally, a filing-based story with no evident connection to Monday’s specific price action in either name. Tempus AI fell 1.55% and American Airlines fell 1.54%, both continuing without fresh dated news attached.

Sources: The Motley Fool (Marvell guidance follow-up by Parkev Tatevosian; Broadcom/Marvell competitive setup by Patrick Sanders; SanDisk revenue-growth comparison by John Ballard; David Tepper 13F piece by Sean Williams), all published August 31–September 1, 2026; Zacks Investment Research (CrowdStrike Falcon IQ and AIDR coverage; SanDisk Zacks Rank #1 upgrade; Micron gross-margin outlook). Price data via Massive Market Data. This article is educational and reflects my own analysis; it is not investment advice.