DOSSIER · 13F-HR · Q1 2026

Main Street Research LLC

Main Street Research's asset manager based in Stamford, CT $1.7B in tracked AUM across 148 positions as of Q1 2026.

MS
Main Street Research·Stamford, CT·Asset Manager
CIK 0001513211 · last filed Mar 31, 2026
Total AUM
$1.7B
18.3%
vs prior
Holdings
148
positions
Whale Score
63
63
tracked
Activity
no data
changes this Q
Top sector
Tech
6% weight
concentration
AI Analysis · Q1 2026 · Q1 2026

A $1.72B book quietly pivoted away from Big Tech darlings this quarter. NVDA remains the top position at 6.3% but the sharpest signal was a 1,950% Micron increase to $36.9M. Discover how this manager rebuilt the portfolio around semiconductor and infrastructure names while nearly exiting Visa, Microsoft, and Palantir.

Quarter at a glance — Q1 2026

Position-change comparison pending.

No quarter-over-quarter changes available.

Top 10 holdings

By portfolio weight as of Q1 2026.

#HoldingValueSharesWeight
01
NVDA
NVIDIA CORPORATION
$108M621K6.3%
02
AAPL
APPLE INC
$102M404K6.0%
03
GOOGL
ALPHABET INC
$90M312K5.2%
04
ISCF
ISHARES TR
$82M2.0M4.8%
05
TSM
TAIWAN SEMICONDUCTOR MANUFAC
$75M223K4.4%
06
XBI
SPDR SERIES TRUST
$72M567K4.2%
07
JPM
JPMORGAN CHASE & CO
$66M224K3.8%
08
AVGO
BROADCOM INC
$66M212K3.8%
09
MCK
MCKESSON CORP
$59M68K3.4%
10
AMZN
AMAZON COM INC
$56M269K3.3%

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