Tsai Capital Corp IDXX — IDEXX LABS INC

Ownership history in Tsai Capital Corp  ·  15 quarters on record

AI Ownership Summary

Tsai Capital Corp reported IDEXX LABS INC (IDXX) in 15 quarterly 13F filings from 2023 Q4 through 2025 Q4. Peak portfolio weight reached 3.19% in 2025 Q1. The latest visible filing shows IDXX at 2.15% of the fund.

This page tracks quarterly shares, estimated market value, portfolio weight, filing dates, and disclosure-aligned stock prices directly from SEC EDGAR 13F filings. Older history is available after unlock; the visible window still shows the most recent pattern.

What this IDXX ownership page tells you

This page is designed to answer the real investor question behind a 13F filing: how meaningful was Tsai Capital Corp's position in IDEXX LABS INC, and how did that conviction change over time? You can read the holding window, peak weight, latest reported size, disclosure timing, and quarter-by-quarter changes without piecing the story together from raw SEC rows.

Freshest filing
Latest Reported Filing
2025 Q4

IDXX was reported at 2.15% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
3.19% in 2025 Q1

Peak weight helps separate a token disclosure from a real conviction holding the fund genuinely cared about.

Time in book
Holding Window
2023 Q4 to 2025 Q4

Longer holding windows often tell a very different story from short-lived tactical trades or one-quarter experiments.

Decision context
Why It Matters
Position size beats headlines

Knowing that a fund owned a stock is useful. Knowing whether it was a 0.20% placeholder or a true high-conviction position is where the signal actually starts.

IDXX stock page Tsai Capital Corp fund profile Tsai Capital Corp full holdings
How Tsai Capital Corp held IDXX — position size vs. price
% of Fund (quarterly)    IDXX price (quarter-end, indexed to 100)    SPY (indexed to 100)    QQQ (indexed to 100)
📋 Quarterly Holdings History 9 quarters  ▾
Quarter Action Sold % After 3M Timing Shares Change Chg % % of Fund Mkt Value Filed Price (Filed)
2025 Q4 ADDED — — — 4,678 +36 +0.8% 2.15% $3.2M 2026-02-14 (Est.) $629.35
2025 Q3 ADDED — — — 4,642 +2 +0.0% 2.07% $3.0M 2025-11-13 $701.48
2025 Q2 REDUCED 49.7% +17.6% ❌ 4,640 -4,585 -49.7% 1.82% $2.5M 2025-08-13 $663.92
2025 Q1 ADDED — — — 9,225 +428 +4.9% 3.19% $3.9M 2025-05-13 $509.13
2024 Q4 ADDED — — — 8,797 +3,016 +52.2% 2.65% $3.6M 2025-02-12 $457.35
2024 Q3 ADDED — — — 5,781 +654 +12.8% 2.37% $2.9M 2024-11-14 $423.65
2024 Q2 UNCHANGED — — — 5,127 — 0% 2.46% $2.5M 2024-08-13 $487.82
2024 Q1 REDUCED — — — 5,127 -158 -3.0% 2.85% $2.8M 2024-05-15 $548.53
2023 Q4 REDUCED 6.2% -4.1% ✅ 5,285 -347 -6.2% 2.69% $2.9M 2024-02-13 $555.66
6 older quarters hidden  —  Sign in free or upgrade to Premium to see full history

🏢 Other funds also holding IDXX

As of 2026 Q1 — sorted by position size

Manitou Investment Management Ltd. 3Y 7Y 7.73% BOURNE LENT ASSET MANAGEMENT INC 3Y 7Y 6.43% Haven Capital Group, Inc. 6.33% Seilern Investment Management Ltd 5.42% PERKINS CAPITAL MANAGEMENT INC 3Y 7Y 5.11% Westwind Capital 3Y 7Y 4.01% HARVEY INVESTMENT CO LLC 3Y 7Y 3.09% MOGY JOEL R INVESTMENT COUNSEL INC 3Y 7Y 3.01% MONTRUSCO BOLTON INVESTMENTS INC. 3Y 7Y 2.83% CARDEROCK CAPITAL MANAGEMENT INC 3Y 7Y 2.29%

FAQ About Tsai Capital Corp and IDXX

These are the practical questions this page is built to answer before you even open the full history table.

How long has Tsai Capital Corp reported owning IDXX?

Tsai Capital Corp reported IDXX across 9 quarterly 13F filings, from 2023 Q4 through 2025 Q4.

What was the largest reported IDXX position in Tsai Capital Corp's portfolio?

The largest reported portfolio weight for IDXX was 3.19% in 2025 Q1.

What is the latest reported IDXX position on this page?

The most recent filing on this page is 2025 Q4, when Tsai Capital Corp reported 4,678 shares, equal to 2.15% of portfolio, with an estimated market value of $3.2M.

What does the chart on this IDXX ownership page compare?

The chart compares Tsai Capital Corp's quarterly IDXX portfolio weight with the stock's indexed share price, so you can see whether the fund was building, trimming, or holding the position as price moved.

How well did Tsai Capital Corp time their IDXX position?

Based on 13F filing dates vs. subsequent IDXX price moves, Tsai Capital Corp correctly timed 6 out of 11 reported position changes (55%). The annualised alpha on IDXX relative to SPY over the holding period was -1.0%.

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