ARKA-PHO · ANALYTICS
Arka Photonics
// WEEKLY SNAPSHOT · 2026-06-26 → 2026-07-02 (5 trading days)
A rough week — Semiconductors (SEMI) exposure alone cost the book about 11%, and stock-picking added more pain.
The book fell about 11% this week as the semiconductor selloff (Korea chip deleveraging, AI-capex jitters after Meta's cloud plans) hit our biggest tilt: Semiconductors (SEMI) exposure alone cost about 11%. Market (MKT) and Growth (GROWTH) tilts actually helped a little, and Aerospace & Defense (DEF) offered almost no offset. About 11% of the total loss was stock-picking the factor model didn't predict, concentrated in names like Amkor and Aehr.
Events this week
- 2026-06-29 South Korea unveiled a major AI/semiconductor industrial strategy anchored by Samsung Electronics and SK Hynix; market read-through was mixed as investors weighed strategic support against future memory-supply-glut risk.[1][2][3]
- 2026-06-29 Asia risk tape was choppy after the prior Korea-led chip deleveraging shock; South Korea's KOSPI pared losses to close only slightly lower as the Korea chip plan and U.S.-Iran truce/talks steadied sentiment.[1][2][3]
- 2026-07-01 Meta reportedly began building a cloud business to sell excess AI compute capacity; this intensified AI capex ROI / overcapacity fears and pressured AI infrastructure and neocloud-exposed names.[1][2][3]
- 2026-07-01 Fed Chair Kevin Warsh, speaking at the ECB forum in Sintra, reiterated commitment to the Fed's 2% inflation target, emphasized independence, and pushed back against giving explicit forward guidance.[1][2][3]
- 2026-07-02 U.S. nonfarm payrolls slowed sharply to 57k jobs in June versus roughly 110k expected; this reduced near-term Fed-hike pressure but added to growth-slowdown concerns.[1][2][3]
- 2026-07-02 U.S. semiconductor selloff intensified: the SOX index fell roughly 5.4% for a second straight down day, with weakness across AI and memory-linked names; Nasdaq underperformed even as the Dow closed at a record.[1][2][3]
- 2026-07-02 Fed's Daly said U.S. policy was “slightly restrictive” and the next move remained uncertain; she highlighted both persistent-inflation risk and the risk that AI investment slows if returns remain unclear.[1][2][3]
- 2026-07-02 Korea/Asia chip deleveraging remained a key global signal: reports showed KOSPI down sharply again, with SK Hynix and Samsung Electronics under heavy pressure as leveraged ETF selling and concerns about large new memory investments amplified volatility.[1][2][3]
- 2026-07-03 Reuters Morning Bid framed the macro tape as “soft jobs, hard choices”: weaker payrolls eased dollar/rate pressure, but chip stocks remained under pressure as investors rotated away from AI-heavy exposure.[1][2][3]
- 2026-07-04 U.S. cash equity markets were closed for the Independence Day holiday; no new U.S. market price signal for the weekly snapshot.[1][2][3]
What actually happened, factor by factor
exactThe week's roughly -11.0% total move breaks down almost entirely to our semiconductor bet: Semiconductors (SEMI) subtracted about -11.0%, while Market (MKT) and Growth (GROWTH) tilts added back a little.
Did our factor tilts predict this?
exactOur factor tilts predicted about -9.7% for the week; the book actually fell about -11.0%. About 11% of that gap was stock-specific moves the model couldn't see coming.
The Semiconductors (SEMI) vs Aerospace & Defense (DEF) barbell didn't help
exactSemiconductors (SEMI) attribution swung from about +2.3% last week to about -11.0% this week (a swing of about -13.1 percentage points versus Aerospace & Defense (DEF)), while Aerospace & Defense (DEF) stayed flat near -0.1%, offering little offset, based on 18 factor-days across both weeks.
Rates barely moved the book this week
exactInterest Rates (RATE) factor returns around the Fed comments and jobs report were close to their typical range (roughly 0.1 standard deviations either way, against over 1,200 days of history) — a short-sample read that may not hold.
No usable read this week
estimateThere wasn't enough matching outside-benchmark data this week to test how closely the book moved with a semiconductor proxy, so no co-movement read is available for this snapshot.
Where the pain actually landed
exactAmkor, Aehr and MACOM led single-name losses (each contributing roughly -2.7% to -1.5% to the total), and 8 of the top 10 negative contributors sat outside our core semis/photonics and space/defense sleeves, across the full book this week.
Chip-adjacent moves were sharper than normal
estimateCoherent (cohr) and photonics peer lite fell about -16.1% and -15.7% over the two trading days around the chip-sector headlines, well below what their recent trend implied — a two-day, short-sample read that may reverse.
Stock-by-stock spread was close to normal
exactThe spread between winners and losers this week (about 4.2%) was only slightly above the past month's typical spread (about 4.0%), and concentration was unchanged — consistent with broad-based pain rather than one crowded corner unwinding (a short-sample read).
How to read this
- Stock-picking
- Name-specific stock moves the factor model doesn't explain — i.e. selection, not the book's factor tilts.
- Factor contribution
- How much each factor exposure (e.g. Market, Semis) added to or subtracted from the week's return.
- Predicted vs Actual
- What the book's factor tilts implied for the week vs what it actually returned; the gap is stock-picking.
- Estimate (short-sample)
- A co-movement read over only ~5 trading days — directional, not statistically reliable, and may not hold.
All event-factor links below are correlations observed in a 5-trading-day window; most are not statistically significant and may reverse. Tier-1 figures are exact accounting identities.
Narrative generated by claude-opus-4-8 (effort high) on 2026-07-05T01:51:44Z — all figures machine-verified against this run’s computed results.