Spero Therapeutics, Inc. (SPRO)
SPRO moved a median of +0.01% 30 minutes after news, and -0.70% by the close. How SPRO actually reacts to news — the realized, point-in-time move the market made, measured across 193 labeled events over the last three years with zero look-ahead.
SPRO’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | 0.00% | 38% | 191 |
| 30-min | +0.01% | 54% | 192 |
| 60-min | 0.00% | 47% | 192 |
| to close | -0.70% | 42% | 192 |
| Middle 50% of SPRO reactions | -1.38% to +1.75% |
|---|---|
| Median reaction (30-min) | +0.01% |
| Measured reactions | 193 |
Half of all Spero Therapeutics, Inc. news events land between -1.38% and +1.75% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
How SPRO reacts, by analyst action.
| Event | Events | Median 30-min | % positive | Median to close |
|---|---|---|---|---|
| Analyst upgrades | 12 | +0.30% | 58% | -2.36% |
| Rating reiterations | 27 | 0.00% | 41% | -3.01% |
Last 3 years, pulled 2026-09-21. Reaction = percent move vs. the price at the news timestamp. Counts and medians only. The same measurement runs across every name in the dataset. 3 further classes were observed with fewer than 10 measured events and are not published. See how SPRO ranks against every other measured name →
That’s how SPRO usually reacts — get an email when it moves on news →Email me when SPRO moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to SPRO's baseline. Nothing else.
Recent SPRO events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Spero Therapeutics to Participate in the Chardan 10th Annual Healthcare Conference | Press release | GlobeNewswire | +0.88% | -3.51% | |
| Spero Therapeutics Announces Inducement Grants Under Nasdaq Listing Rule 5635(c)(4) | Press release | GlobeNewswire | +1.28% | -0.85% | |
| Form EFFECT Spero Therapeutics, Inc. | SEC filing · Form EFFECT | SEC EDGAR | +0.00% | +0.00% | |
| Spero Therapeutics Announces Inducement Grant Under Nasdaq Listing Rule 5635(c)(4) | Press release | GlobeNewswire | +1.26% | +0.83% | |
| Spero Therapeutics to Present at H.C. Wainwright 28th Annual Global Investment Conference | Press release | GlobeNewswire | +0.00% | +0.00% | |
| Form 8-K Spero Therapeutics, Inc. For: Aug 28 | SEC filing · Form 8-K | SEC EDGAR | +2.33% | +1.67% | |
| Form S-3 Spero Therapeutics, Inc. | SEC filing · Form S-3 | SEC EDGAR | +2.33% | +1.67% | |
| Form 10-Q Spero Therapeutics, Inc. For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | -0.40% | -1.59% | |
| Form 8-K Spero Therapeutics, Inc. For: Aug 12 | SEC filing · Form 8-K | SEC EDGAR | -0.40% | -1.59% | |
| Spero Therapeutics Announces Second Quarter 2026 Operating Results and Provides Business Update | Press release | GlobeNewswire | -0.40% | -1.59% | |
| Spero Therapeutics Announces Inducement Grant Under Nasdaq Listing Rule 5635(c)(4) | Press release | GlobeNewswire | -1.98% | +0.79% | |
| Spero Therapeutics to Report Second Quarter 2026 Financial Results and Provide Business Update on August 12, 2026 | Press release | GlobeNewswire | -0.40% | +0.80% | |
| Spero Therapeutics Appoints Debra Jeske Zack, M.D., Ph.D., as Chief Medical Officer | Press release | GlobeNewswire | -2.50% | -1.67% | |
| Form 8-K Spero Therapeutics, Inc. For: Jul 08 | SEC filing · Form 8-K | SEC EDGAR | +0.94% | -20.93% | |
| Innovent Biologics and Spero Therapeutics Announce Exclusive License for IBI355 (SP001), a Phase 2-Ready Third-Generation Anti-CD40L Antibody | Press release | PR Newswire | +0.94% | -20.93% | |
| Spero Therapeutics and Innovent Biologics Announce Exclusive License for SP001 (IBI355), a Phase 2-Ready Third-Generation Anti-CD40L Antibody | Press release | GlobeNewswire | +0.94% | -20.93% | |
| Spero Therapeutics Announces $105 Million Non-Recourse Non-Dilutive Financing Backed by a Portion of Utebzi Milestones & Royalties | Press release | GlobeNewswire | +0.94% | -20.93% | |
| Form 8-K Spero Therapeutics, Inc. For: Jun 23 | SEC filing · Form 8-K | SEC EDGAR | +1.99% | +12.44% | |
| Form S-8 Spero Therapeutics, Inc. | SEC filing · Form S-8 | SEC EDGAR | +2.79% | -2.33% | |
| Form 8-K Spero Therapeutics, Inc. For: Jun 17 | SEC filing · Form 8-K | SEC EDGAR | +0.93% | -0.46% | |
| Utebzi (tebipenem pivoxil) approved in the US for adults with complicated urinary tract infections (cUTIs) | Press release | GlobeNewswire | +0.25% | -6.64% | |
| Form 10-Q Spero Therapeutics, Inc. For: Mar 31 | SEC filing · Form 10-Q | SEC EDGAR | -0.82% | +13.12% | |
| Form 8-K Spero Therapeutics, Inc. For: May 13 | SEC filing · Form 8-K | SEC EDGAR | -0.82% | +13.12% | |
| Spero Therapeutics Announces First Quarter 2026 Operating Results and Provides Business Update | Press release | GlobeNewswire | -0.82% | +13.12% | |
| Spero Therapeutics to Report First Quarter 2026 Financial Results and Provide Business Update on May 13, 2026 | Press release | GlobeNewswire | -1.22% | +2.43% | |
| Form ARS Spero Therapeutics, Inc. For: Dec 31 | SEC filing · Form ARS | SEC EDGAR | +0.00% | -0.37% | |
| Form DEF 14A Spero Therapeutics, Inc. For: Jun 23 | SEC filing · Form DEF | SEC EDGAR | +0.00% | -0.37% | |
| Form DEFA14A Spero Therapeutics, Inc. | SEC filing · Form DEFA14A | SEC EDGAR | +0.00% | -0.37% | |
| Form PRE 14A Spero Therapeutics, Inc. For: Jun 23 | SEC filing · Form PRE | SEC EDGAR | +0.00% | -2.11% | |
| Form 10-K Spero Therapeutics, Inc. For: Dec 31 | SEC filing · Form 10-K | SEC EDGAR | +2.63% | +2.19% | |
| Form 8-K Spero Therapeutics, Inc. For: Mar 26 | SEC filing · Form 8-K | SEC EDGAR | +2.63% | +2.19% | |
| Spero Therapeutics Announces Fourth Quarter and Full Year 2025 Operating Results and Provides a Business Update | Press release | GlobeNewswire | +2.63% | +2.19% | |
| Spero Therapeutics to Report Fourth Quarter and Full Year 2025 Financial Results and Provide Business Update on March 26, 2026 | Press release | GlobeNewswire | -1.02% | +0.82% | |
| Form 8-K Spero Therapeutics, Inc. For: Jan 30 | SEC filing · Form 8-K | SEC EDGAR | +1.40% | +3.72% | |
| Form 8-K Spero Therapeutics, Inc. For: Dec 19 | SEC filing · Form 8-K | SEC EDGAR | +1.06% | -1.28% | |
| Spero Announces NDA Resubmission of Tebipenem HBr by GSK to the FDA for the Treatment of Complicated Urinary Tract Infections, Including Pyelonephritis | Press release | GlobeNewswire | +1.06% | -1.28% | |
| Spero Therapeutics Announces Inducement Grant Under Nasdaq Listing Rule 5635(c)(4) | Press release | GlobeNewswire | +1.70% | +2.13% | |
| Spero Therapeutics to Report Third Quarter 2025 Financial Results and Provide Business Update on November 13, 2025 | Press release | GlobeNewswire | +2.11% | +3.40% | |
| PIVOT-PO Phase 3 Data Show Tebipenem HBr’s Potential as the First Oral Carbapenem Antibiotic for Patients with Complicated Urinary Tract Infections (cUTIs) | Press release | GlobeNewswire | +3.91% | +3.04% | |
| Spero Therapeutics Announces Presentations on Tebipenem Hbr at IDWeek | Press release | GlobeNewswire | +1.79% | +5.36% | |
| Form 10-Q Spero Therapeutics, Inc. For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | -6.14% | -10.00% | |
| Form 8-K Spero Therapeutics, Inc. For: Aug 12 | SEC filing · Form 8-K | SEC EDGAR | -6.14% | -10.00% | |
| Form S-8 Spero Therapeutics, Inc. | SEC filing · Form S-8 | SEC EDGAR | -6.14% | -10.00% | |
| Spero Therapeutics Announces Second Quarter 2025 Operating Results and Provides a Business Update | Press release | GlobeNewswire | -6.14% | -10.00% | |
| Spero Therapeutics to Report Second Quarter 2025 Financial Results and Provide Business Update on Tuesday, August 12, 2025 | Press release | GlobeNewswire | +1.40% | +5.12% | |
| Form 8-K Spero Therapeutics, Inc. For: Jun 12 | SEC filing · Form 8-K | SEC EDGAR | -0.51% | +3.07% | |
| Form 8-K Spero Therapeutics, Inc. For: May 28 | SEC filing · Form 8-K | SEC EDGAR | +8.74% | +14.08% | |
| Spero Therapeutics and GSK Announce PIVOT-PO Phase 3 Study for Tebipenem HBr Stopped Early for Efficacy Following Review by Independent Data Monitoring Committee | Press release | GlobeNewswire | +8.74% | +14.08% | |
| Form 10-Q Spero Therapeutics, Inc. For: Mar 31 | SEC filing · Form 10-Q | SEC EDGAR | +0.00% | -7.13% | |
| Form 8-K Spero Therapeutics, Inc. For: May 13 | SEC filing · Form 8-K | SEC EDGAR | +0.00% | -7.13% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the SPRO section they belong to.
Where else SPRO is measured.
SPRO earnings → · Analyst actions → · SEC filings →
Other Healthcare names, measured the same way
| Ticker | Events | Median 30-min | % positive |
|---|---|---|---|
| PAVmed Inc. (PAVM) | 193 | -0.49% | 41% |
| SIENNA BIOPHARMACEUTICALS (SNNA) | 193 | 0.00% | 40% |
| Xtant Medical Holdings, Inc. (XTNT) | 193 | 0.00% | 42% |
| Apollo Medical Holdings, Inc. (AMEH) | 192 | +0.16% | 55% |
Same sector, same measurement: percent move vs. the price at the news timestamp, read at 30 minutes. Sample sizes differ, so the medians are comparable but the confidence behind them is not.
All Healthcare names, measured the same way →
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How the numbers are made.
How is Spero Therapeutics, Inc.'s median reaction calculated?
Every labeled SPRO news event is measured from its own timestamp: the last trade before the news is the base price, and the move is read at fixed horizons — 30 minutes of trading, then the close. The median across 193 events is what this page reports. Point-in-time, zero look-ahead: no event borrows information from a later one.
What counts as a positive reaction?
Any event whose price move is above zero at the horizon, relative to the last trade before the news timestamp. 54% of SPRO's measured events are up at 30 minutes; the rest close the window flat or negative.
How often is this page updated?
The news table refreshes automatically as new events are labeled and priced. The reaction medians are re-pulled in batches from the dataset — the figures here are as of 2026-09-21.
Does SPRO's past reaction predict its next one?
No. These are realized facts about past events, not forecasts. They describe a distribution — they say nothing certain about any future move.