BEACONLIGHT CAPITAL, LLC TNDM — TANDEM DIABETES CARE INC

Ownership history in BEACONLIGHT CAPITAL, LLC  ·  8 quarters on record

AI Ownership Summary

BEACONLIGHT CAPITAL, LLC reported TANDEM DIABETES CARE INC (TNDM) in 8 quarterly 13F filings from 2023 Q4 through 2026 Q1. Peak portfolio weight reached 4.42% in 2024 Q4. The latest visible filing shows TNDM at 2.56% 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 TNDM ownership page tells you

This page is designed to answer the real investor question behind a 13F filing: how meaningful was BEACONLIGHT CAPITAL, LLC's position in TANDEM DIABETES CARE 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

TNDM was reported at 2.56% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
4.42% in 2024 Q4

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 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.

TNDM stock page BEACONLIGHT CAPITAL, LLC fund profile BEACONLIGHT CAPITAL, LLC full holdings
How BEACONLIGHT CAPITAL, LLC held TNDM — position size vs. price
% of Fund (quarterly)    TNDM price (quarter-end, indexed to 100)    SPY (indexed to 100)    QQQ (indexed to 100)
📋 Quarterly Holdings History 8 quarters  ▾
Quarter Action Sold % After 3M Timing Shares Change Chg % % of Fund Mkt Value Filed Price (Filed)
2026 Q1 ADDED — — — 253,877 +200,422 +374.9% 2.56% $4.9M 2026-05-14 $14.15
2025 Q2 REDUCED 75.7% -36.8% ✅ 53,455 -166,302 -75.7% 0.57% $996K 2025-08-14 $10.66
2025 Q1 REDUCED 33.7% -2.7% ✅ 219,757 -111,452 -33.7% 2.82% $4.2M 2025-05-15 $22.70
2024 Q4 ADDED — — — 331,209 +115,594 +53.6% 4.42% $11.9M 2025-02-14 $33.47
2024 Q3 ADDED — — — 215,615 +94,317 +77.8% 3.72% $9.1M 2024-11-13 $29.67
2024 Q2 REDUCED 50.9% +5.3% ❌ 121,298 -125,888 -50.9% 2.19% $4.9M 2024-08-14 $41.71
2024 Q1 ADDED — — — 247,186 +180,859 +272.7% 3.49% $8.8M 2024-05-14 $44.07
2023 Q4 INITIATED — — — 66,327 — — 0.80% $2.0M 2024-02-13 $24.55

🏢 Other funds also holding TNDM

As of 2026 Q1 — sorted by position size

Paradice Investment Management LLC 3Y 7Y 7.35% First Light Asset Management, LLC 3Y 7Y 2.26% Defilade Capital Management, L.P. 2.05% Sessa Capital IM, L.P. 3Y 7Y 1.65% ArrowMark Colorado Holdings LLC 3Y 7Y 1.58% DAFNA Capital Management LLC 3Y 7Y 1.55% SECTOR GAMMA AS 3Y 7Y 1.21% Lisanti Capital Growth, LLC 3Y 7Y 0.8% Nierenberg Investment Management Company, LLC 3Y 7Y 0.76% FORMULA GROWTH LTD 3Y 7Y 0.61%

FAQ About BEACONLIGHT CAPITAL, LLC and TNDM

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

How long has BEACONLIGHT CAPITAL, LLC reported owning TNDM?

BEACONLIGHT CAPITAL, LLC reported TNDM across 8 quarterly 13F filings, from 2023 Q4 through 2026 Q1.

What was the largest reported TNDM position in BEACONLIGHT CAPITAL, LLC's portfolio?

The largest reported portfolio weight for TNDM was 4.42% in 2024 Q4.

What is the latest reported TNDM position on this page?

The most recent filing on this page is 2026 Q1, when BEACONLIGHT CAPITAL, LLC reported 253,877 shares, equal to 2.56% of portfolio, with an estimated market value of $4.9M.

What does the chart on this TNDM ownership page compare?

The chart compares BEACONLIGHT CAPITAL, LLC's quarterly TNDM 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 BEACONLIGHT CAPITAL, LLC time their TNDM position?

Based on 13F filing dates vs. subsequent TNDM price moves, BEACONLIGHT CAPITAL, LLC correctly timed 4 out of 7 reported position changes (57%). The annualised alpha on TNDM relative to SPY over the holding period was -52.6%.

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