Boston Trust Walden Corp AMPH — AMPHASTAR PHARMACEUTICALS INC

Ownership history in Boston Trust Walden Corp  ·  7 quarters on record

AI Ownership Summary

Boston Trust Walden Corp reported AMPHASTAR PHARMACEUTICALS INC (AMPH) in 7 quarterly 13F filings from 2024 Q3 through 2026 Q1. Peak portfolio weight reached 0.26% in 2025 Q1. The latest visible filing shows AMPH at 0.15% 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.

What this AMPH ownership page tells you

This page is designed to answer the real investor question behind a 13F filing: how meaningful was Boston Trust Walden Corp's position in AMPHASTAR PHARMACEUTICALS 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
2026 Q1

AMPH was reported at 0.15% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
0.26% 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
2024 Q3 to 2026 Q1

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.

AMPH stock page Boston Trust Walden Corp fund profile Boston Trust Walden Corp full holdings
How Boston Trust Walden Corp held AMPH — position size vs. price
% of Fund (quarterly)    AMPH price (quarter-end, indexed to 100)    SPY (indexed to 100)    QQQ (indexed to 100)
📋 Quarterly Holdings History 7 quarters  ▾
Quarter Action Sold % After 3M Timing Shares Change Chg % % of Fund Mkt Value Filed Price (Filed)
2026 Q1 REDUCED — — — 944,789 -142,477 -13.1% 0.15% $18.5M 2026-04-24 $21.41
2025 Q4 REDUCED 7.3% -26.9% ✅ 1,087,266 -85,841 -7.3% 0.22% $29.1M 2026-01-28 $26.12
2025 Q3 REDUCED — — — 1,173,107 -3,346 -0.3% 0.23% $31.3M 2025-10-17 $23.78
2025 Q2 REDUCED — — — 1,176,453 -39,171 -3.2% 0.19% $27.0M 2025-07-28 $22.24
2025 Q1 ADDED — — — 1,215,624 +236,704 +24.2% 0.26% $35.2M 2025-04-21 $23.50
2024 Q4 ADDED — — — 978,920 +439,281 +81.4% 0.26% $36.3M 2025-01-24 $36.50
2024 Q3 INITIATED — — — 539,639 — — 0.18% $26.2M 2024-10-24 $49.63

🏢 Other funds also holding AMPH

As of 2026 Q1 — sorted by position size

LAM GROUP, INC. 3Y 1.41% SummerHaven Investment Management, LLC 3Y 0.39% EXCHANGE TRADED CONCEPTS, LLC 3Y 0.01% State of Alaska, Department of Revenue 3Y 7Y 0.01% Louisiana State Employees Retirement System 3Y 7Y 0.01% Sterling Capital Management LLC 3Y 7Y 0.0% Robeco Institutional Asset Management B.V. 3Y 7Y 0.0% CX Institutional 3Y 7Y 0.0% Bank of New Hampshire 3Y 0.0% City State Bank 3Y 0.0%

FAQ About Boston Trust Walden Corp and AMPH

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

How long has Boston Trust Walden Corp reported owning AMPH?

Boston Trust Walden Corp reported AMPH across 7 quarterly 13F filings, from 2024 Q3 through 2026 Q1.

What was the largest reported AMPH position in Boston Trust Walden Corp's portfolio?

The largest reported portfolio weight for AMPH was 0.26% in 2025 Q1.

What is the latest reported AMPH position on this page?

The most recent filing on this page is 2026 Q1, when Boston Trust Walden Corp reported 944,789 shares, equal to 0.15% of portfolio, with an estimated market value of $18.5M.

What does the chart on this AMPH ownership page compare?

The chart compares Boston Trust Walden Corp's quarterly AMPH 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 Boston Trust Walden Corp time their AMPH position?

Based on 13F filing dates vs. subsequent AMPH price moves, Boston Trust Walden Corp correctly timed 1 out of 6 reported position changes (17%). The annualised alpha on AMPH relative to SPY over the holding period was -63.5%.

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