What is the 13F Pro Quality Score for SPRO?

13F Pro ranks Spero Therapeutics, Inc. (SPRO) on the 13F Pro Quality Score, a 0–100 composite of 32 fundamental signals including return on invested capital, free cash flow consistency, balance-sheet strength, earnings quality, growth durability, and valuation discipline. The score refreshes after each 10-K and 10-Q filing on SEC EDGAR. View SPRO's current score at https://13fpro.ai/research/SPRO (free sign-up required for the full ranking).

Which hedge funds own the most SPRO stock?

Based on the most recent Form 13F-HR filings on SEC EDGAR, the largest reported institutional holders of SPRO include GSK plc, PFIZER, VANGUARD CAPITAL MANAGEMENT. Holdings are reported quarterly within 45 days of quarter-end and updated on https://13fpro.ai/research/SPRO as soon as new 13F filings post.

Where does 13F Pro source SPRO data?

All Spero Therapeutics, Inc. fundamentals and ownership data come directly from SEC EDGAR. Spero Therapeutics, Inc. files with the SEC under CIK 1701108. 13F Pro ingests XBRL financial facts from 10-K and 10-Q filings, Form 13F-HR institutional holdings, and Form 4 insider transactions, with no third-party rewrites or estimates.

What sector is SPRO in?

Spero Therapeutics, Inc. (SPRO) is classified in the Healthcare sector. 13F Pro publishes sector-level fund flow analysis and quality leaders at https://13fpro.ai/research/sector/healthcare.

How often is SPRO research updated on 13F Pro?

SPRO's fundamentals refresh within hours of each new 10-K or 10-Q filing on SEC EDGAR. Institutional ownership updates after each quarterly 13F filing window. Insider transactions update after each Form 4 filing. The 13F Pro Quality Score recalculates after every fundamentals refresh.

Spero Therapeutics, Inc.(SPRO)Stock Analysis

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13F Pro Quality Score

19.5/100

Rank #2,690 of 2,860 stocks

View Healthcare peers →

Rankings refresh quarterly once 80% of peers have filed (~45 days after quarter-end). Next update: ~Aug 14, 2026.

Revenue Growth

0.2/100

Profitability

0.1/100

Balance Sheet

4.1/100

Earnings Quality

30.0/100

Free Cash Flow

99.9/100

Institutional Flow

24.9/100

Dilution Risk

22.3/100

SPRO Stock Analysis & AI Quality Score

AI stock analysis and institutional research for Spero Therapeutics, Inc. (SPRO), a Healthcare sector company. 13F Pro's AI-powered ranking engine scores SPRO at 19.5/100 on a 32-signal composite quality model, placing it at rank #2,690 of 2,860 stocks — the bottom half of the AI-ranked universe. SPRO scores in the top quartile across free cash flow (99.9). Areas of concern include profitability (0.1) and revenue growth (0.2), which score below median versus the broader universe. Shareholder dilution risk is elevated at 22.3/100, reflecting ongoing share issuance or stock-based compensation. Based on the latest XBRL financial filings (Q1 2026), Spero Therapeutics, Inc. reports quarterly revenue of $258.0K, net income of $-7.2M, free cash flow of $15.9M. Top institutional holders of SPRO by reported 13-F value include GSK plc, PFIZER, VANGUARD CAPITAL MANAGEMENT, based on the most recent SEC filings. SPRO trades on the Nasdaq exchange and files with the SEC under CIK 1701108. 13F Pro's AI research platform runs 10 specialized AI analysts — value, growth, momentum, macro, and activist specialists — that debate SPRO daily and publish AI-generated analysis with cited SEC sources. The platform aggregates historical XBRL financial facts, 10-Q and 10-K filings, insider Form 4 transactions, and institutional 13-F holdings for Spero Therapeutics, Inc. directly from SEC EDGAR. Spero Therapeutics, Inc.'s 13F Pro composite quality score has ranged between 3 and 44 since 2021, currently 19.5 — a stable long-term trajectory across 30 quarterly and live scoring snapshots.

✦

Fun facts about Spero Therapeutics, Inc.

Quirks, history, and lore behind SPRO — the kind of stuff that makes a stock memorable.

1
The Basics
U.S. biopharmaceutical company · focused on serious bacterial infections · listed on Nasdaq · headquartered in Cambridge, Massachusetts.
2
The Numbers
A small-cap clinical-stage company with limited commercial revenue — the kind of balance sheet where every pipeline update moves the stock by double digits.
3
The History
Founded in the mid-2010s, it was built around tackling antimicrobial resistance — one of medicine's most stubborn and underfunded problems.
4
The Secret
Its pipeline targets multidrug-resistant (MDR) pathogens, the bacteria that laugh at standard antibiotics — a niche most big pharma companies have largely abandoned.
5
The Lore
The company's name is derived from the Latin word for "hope" — fitting for a firm betting that the world will finally pay attention to the antibiotic resistance crisis.
6
The Giveaway
Ticker SPRO, named for hope, fighting superbugs from Cambridge — this is Spero Therapeutics.

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Revenue

Q1 2026

$258.0K

Net Income

Q1 2026

$-7.2M

Free Cash Flow

Q1 2026

$15.9M

Revenue & Net Income

Earnings Per Share

Key Financials Over Time

Export Financial Table · Pro+

Revenue

+94.0% YoY

$103.8MFY 2023

FY20 $9.3MFY21 $18.3MFY22 $53.5MFY23 $103.8M

Net Income

$22.8MFY 2023

FY20 $-78.3MFY21 $-89.8MFY22 —FY23 $22.8M

Operating Income

+150.9% YoY

$21.5MFY 2023

FY20 $-79.1MFY21 $-88.0MFY22 $-42.2MFY23 $21.5M

EPS (Diluted)

+135.0% YoY

$0.43FY 2023

FY20 —FY21 $-2.91FY22 $-1.23FY23 $0.43

Total Assets

+46.1% YoY

$182.4MFY 2023

FY20 $153.5MFY21 $171.1MFY22 $124.8MFY23 $182.4M

Op. Cash Flow

-326.8% YoY

$-33.0MFY 2023

FY20 $-85.9MFY21 $-64.3MFY22 $-7.7MFY23 $-33.0M

Metric	FY 2023	FY 2022	FY 2021	FY 2020	FY 2017	FY 2015
Revenue	$103.8M +94.0%	$53.5M +193.1%	$18.3M +95.7%	$9.3M +371.5%	$2.0M	—
Net Income	$22.8M	—	$-89.8M -14.7%	$-78.3M -102.1%	$-38.7M -281.6%	$-10.2M
Operating Income	$21.5M +150.9%	$-42.2M +52.0%	$-88.0M -11.2%	$-79.1M -89.6%	$-41.7M -213.1%	$-13.3M
EPS (Diluted)	$0.43 +135.0%	$-1.23 +57.7%	$-2.91	—	—	—
Total Assets	$182.4M +46.1%	$124.8M -27.0%	$171.1M +11.5%	$153.5M +64.2%	$93.5M	—
Operating Cash Flow	$-33.0M -326.8%	$-7.7M +88.0%	$-64.3M +25.1%	$-85.9M -119.6%	$-39.1M	—

AI Insight: SPRO Financial Trends

Spero swung to profitability in Q4 2025 with $41M revenue and $32M net income, but Q1 2026 collapsed to zero revenue and resumed losses.

• Operating income improved dramatically from -$8M in Q3 2025 to +$31M in Q4 2025, driven by $41M revenue spike.

• Net income turned positive at $32M in Q4 2025, the only profitable quarter in the 8-quarter span.

• Equity recovered from $26M (Q3 2025) to $59M (Q4 2025), then declined to $53M in Q1 2026.

⚠ Q1 2026 revenue collapsed to $0M with -$7M net loss; Q4 2025 $41M appears to be one-time event, not sustained.

⚠ Operating cash flow highly volatile: +$17M (Q3 2025), -$8M (Q4 2025), +$16M (Q1 2026) — no clear trend.

AI Insight: SPRO Ratio Trends

Spero swung from deep losses to profitability in Q4 2025, but Q1 2026 shows a sharp pullback into negative returns across all metrics.

• Operating margin surged to 76.0% in Q4 2025 from -145.5% in Q3 2025, driven by a major profitability inflection.

• TTM operating margin now 22.1% and net profit margin 24.9%, reflecting strong recent quarters offsetting prior-year losses.

• Q1 2026 ROE collapsed to -54.4%, ROA to -48.8%, and ROIC to -57.0%, erasing Q4 2025's gains.

⚠ Extreme quarterly volatility: OpMargin swung 221pp from Q3 2025 to Q4 2025, then reversed sharply in Q1 2026. Underlying drivers unclear.

⚠ Q1 2026 return metrics turned deeply negative despite TTM profitability, suggesting Q4 was an outlier or one-time event.

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Available Research

13F Pro tracks comprehensive data for Spero Therapeutics, Inc. including:

SEC EDGAR filings (10-K, 10-Q, 8-K)

XBRL financial facts (revenue, EPS, margins)

Insider transactions (Form 4)

Institutional 13F holdings

Quality rankings (32 signals)

AI analyst debates & daily meetings

Historical financial trends

Peer comparison & sector analysis

Top Institutional Holders of SPRO

GSK plc
$21.5M9,190,606 sh
PFIZER INC
$5.5M2,362,348 sh
VANGUARD CAPITAL MANAGEMENT LLC
$4.2M1,799,880 sh
RENAISSANCE TECHNOLOGIES LLC
$2.8M1,189,235 sh
Alphabet Inc.
$2.1M889,979 sh
TWO SIGMA INVESTMENTS, LP
$2.1M885,631 sh
GEODE CAPITAL MANAGEMENT, LLC
$1.2M519,922 sh
BlackRock, Inc.
$1.0M433,202 sh
Anson Funds Management LP
$987.4K421,956 sh
CITADEL ADVISORS LLC
$880.9K376,458 sh

Fund	Value	Shares
GSK plc	$21.5M	9,190,606
PFIZER INC	$5.5M	2,362,348
VANGUARD CAPITAL MANAGEMENT LLC	$4.2M	1,799,880
RENAISSANCE TECHNOLOGIES LLC	$2.8M	1,189,235
Alphabet Inc.	$2.1M	889,979
TWO SIGMA INVESTMENTS, LP	$2.1M	885,631
GEODE CAPITAL MANAGEMENT, LLC	$1.2M	519,922
BlackRock, Inc.	$1.0M	433,202
Anson Funds Management LP	$987.4K	421,956
CITADEL ADVISORS LLC	$880.9K	376,458

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Is SPRO a good stock to buy?

13F Pro's AI-powered analysis of Spero Therapeutics, Inc. (SPRO) draws on SEC EDGAR-sourced fundamentals, institutional 13F holdings, and insider Form 4 transactions in the Healthcare sector (listed on Nasdaq). The 32-signal AI Quality Score, current rank, and full bull/bear verdict for SPRO are available on the SPRO stock profile dashboard — with the same data, AI insights, ratios, and institutional activity refreshed after every 10-K, 10-Q, 13F, and Form 4 filing.

Which hedge funds own SPRO?

Institutional investors are required to disclose their holdings quarterly via SEC Form 13F. 13F Pro aggregates these filings to show which hedge funds, mutual funds, and asset managers are buying or selling SPRO. Combined with insider transaction data from Form 4 filings and AI-powered analysis from 10 specialized research agents, 13F Pro provides a comprehensive view of Spero Therapeutics, Inc.'s investment landscape.