SIMPLEX TRADING, LLC SPRO — SPERO THERAPEUTICS INC

Ownership history in SIMPLEX TRADING, LLC  ·  15 quarters on record

AI Ownership Summary

SIMPLEX TRADING, LLC reported SPERO THERAPEUTICS INC (SPRO) in 15 quarterly 13F filings from 2024 Q3 through 2026 Q1. The latest visible filing shows SPRO at 0.00% 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 SPRO ownership page tells you

This page is designed to answer the real investor question behind a 13F filing: how meaningful was SIMPLEX TRADING, LLC's position in SPERO THERAPEUTICS 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

SPRO was reported at 0.00% of portfolio in the most recent visible filing.

High-water mark
Peak Conviction
0.0% in 2025 Q2

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.

SPRO stock page SIMPLEX TRADING, LLC fund profile SIMPLEX TRADING, LLC full holdings
How SIMPLEX TRADING, LLC held SPRO — position size vs. price
% of Fund (quarterly)    SPRO 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 — — — 30,304 -5,382 -15.1% 0.00% $71K 2026-05-14 $2.76
2025 Q4 ADDED — — — 35,686 +28,068 +368.4% 0.00% $83K 2026-02-11 $2.37
2025 Q3 REDUCED 74.9% +22.3% ❌ 7,618 -22,704 -74.9% 0.00% $14K 2025-11-12 $2.66
2025 Q2 ADDED — — — 30,322 +25,224 +494.8% 0.00% $87K 2025-08-05 $2.12
2025 Q1 REDUCED — — — 5,098 -12 -0.2% 0.00% $3K 2025-05-12 $0.61
2024 Q4 ADDED — — — 5,110 +4,189 +454.8% 0.00% $5K 2025-02-11 $0.82
2024 Q3 REDUCED 59.6% -23.9% ✅ 921 -1,360 -59.6% 0.00% $1K 2024-11-08 $1.32
8 older quarters hidden  —  Sign in free or upgrade to Premium to see full history

🏢 Other funds also holding SPRO

As of 2026 Q1 — sorted by position size

GSK plc 3.59% PFIZER INC 2.31% Anson Funds Management LP 3Y 7Y 0.09% Alphabet Inc. 3Y 0.05% GSA CAPITAL PARTNERS LLP 3Y 7Y 0.04% Three Seasons Wealth, LLC 0.03% Torrey Growth & Income Advisors 0.02% FNY Investment Advisers, LLC 3Y 7Y 0.01% RENAISSANCE TECHNOLOGIES LLC 3Y 7Y 0.0% Capital Asset Advisory Services LLC 3Y 7Y 0.0%

FAQ About SIMPLEX TRADING, LLC and SPRO

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

How long has SIMPLEX TRADING, LLC reported owning SPRO?

SIMPLEX TRADING, LLC reported SPRO across 7 quarterly 13F filings, from 2024 Q3 through 2026 Q1.

What was the largest reported SPRO position in SIMPLEX TRADING, LLC's portfolio?

The largest reported portfolio weight for SPRO was 0.00% in 2025 Q2.

What is the latest reported SPRO position on this page?

The most recent filing on this page is 2026 Q1, when SIMPLEX TRADING, LLC reported 30,304 shares, equal to 0.00% of portfolio, with an estimated market value of $71K.

What does the chart on this SPRO ownership page compare?

The chart compares SIMPLEX TRADING, LLC's quarterly SPRO 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 SIMPLEX TRADING, LLC time their SPRO position?

Based on 13F filing dates vs. subsequent SPRO price moves, SIMPLEX TRADING, LLC correctly timed 9 out of 14 reported position changes (64%). The annualised alpha on SPRO relative to SPY over the holding period was -24.6%.

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