Fastly
A latent Fastly software bug triggered by a valid customer configuration caused a broad global outage across its edge network.
+8.5% FSLY vs +2.4% SPY
This site shows how share prices moved after an incident became public. It does not prove that the incident caused the move. Company news, sector moves and the wider market can affect every result. Educational only — not investment advice.
Disclosure timing
When could the market react?
The baseline is the last adjusted close before the news was public. The reaction session is the first close afterward.
- 01Baseline sessionJun 7, 2021
Normalized to 100 for both FSLY and SPY.
- 02Public disclosureJun 8, 2021, 5:58 AM EDT
Documented publication time.
- 03First reaction closeJun 8, 2021
+10.8% company total return versus +0.0% for SPY; +10.8 pp market-relative return.
Time windows
Company vs SPY
Each row uses the last trading session on or before its target date. “Market-relative” is the company return minus the SPY return, in percentage points.
| Window | Endpoint | FSLY | SPY | Market-relative | Signal |
|---|---|---|---|---|---|
| First reaction | Jun 8, 2021 | +10.8% | +0.0% | +10.8 pp | Above SPY |
| +7 days | Jun 15, 2021 | +7.6% | +0.5% | +7.0 pp | Above SPY |
| +1 month | Jul 8, 2021 | +8.5% | +2.4% | +6.1 pp | Above SPY |
| +3 months | Sep 8, 2021 | -11.0% | +7.2% | -18.1 pp | Below SPY |
| +6 months | Dec 8, 2021 | -14.8% | +11.9% | -26.7 pp | Below SPY |
| +12 months | Jun 8, 2022 | -73.6% | -1.3% | -72.3 pp | Below SPY |
Compare with current catalog aggregates
| Window | This case | Catalog median | Catalog mean | n |
|---|---|---|---|---|
| First reaction | +10.8 pp | -0.8 pp | -1.5 pp | 30 |
| +7 days | +7.0 pp | -2.0 pp | -4.0 pp | 30 |
| +1 month | +6.1 pp | -6.6 pp | -6.8 pp | 30 |
| +3 months | -18.1 pp | -5.1 pp | -6.6 pp | 30 |
| +6 months | -26.7 pp | -5.6 pp | -7.5 pp | 30 |
| +12 months | -72.3 pp | -3.7 pp | -10.1 pp | 30 |
Normalized total return
FSLY compared with SPY
Baseline session = 100. Adjusted close reflects splits and reinvested distributions.
Fastly had -73.6% company total return versus -1.3% for SPY; -72.3 pp market-relative return. The chart shows normalized adjusted-close performance for up to 24 months.
View tabular chart fallback
| Date | FSLY | SPY |
|---|---|---|
| Jun 7, 2021 | 100.0 | 100.0 |
| Jul 7, 2021 | 107.2 | 103.2 |
| Aug 5, 2021 | 78.8 | 105.0 |
| Sep 3, 2021 | 92.1 | 107.7 |
| Oct 5, 2021 | 75.0 | 103.2 |
| Nov 3, 2021 | 105.2 | 110.8 |
| Dec 3, 2021 | 70.8 | 108.1 |
| Jan 4, 2022 | 68.0 | 114.2 |
| Feb 3, 2022 | 50.4 | 106.8 |
| Mar 7, 2022 | 29.6 | 100.3 |
| Apr 5, 2022 | 36.3 | 108.2 |
| May 5, 2022 | 27.2 | 99.3 |
| Jun 6, 2022 | 24.5 | 98.8 |
| Jul 7, 2022 | 27.7 | 93.8 |
| Aug 5, 2022 | 22.2 | 99.7 |
| Sep 6, 2022 | 17.7 | 94.2 |
| Oct 5, 2022 | 18.4 | 91.3 |
| Nov 3, 2022 | 17.3 | 89.8 |
| Dec 5, 2022 | 19.1 | 96.7 |
| Jan 5, 2023 | 16.3 | 92.2 |
| Feb 6, 2023 | 21.5 | 99.6 |
| Mar 8, 2023 | 30.3 | 97.0 |
| Apr 6, 2023 | 31.0 | 99.9 |
| May 8, 2023 | 24.6 | 100.7 |
| Jun 7, 2023 | 32.5 | 104.1 |
| Jun 8, 2023 | 33.3 | 104.7 |
Media attention · first 14 days
How this incident was covered
Written articles whose recorded headline explicitly names Fastly, recovered from a fixed panel of seven US publisher families. This is an observed lower bound, not a count of all coverage.
Publication pace
Publisher mix
What the recorded headline emphasized
These local labels describe headline wording. They do not measure reader sentiment, publisher stance, blame, or reputational impact.
- DescriptiveIdentifies or explains the event.
- 1
- Adverse eventEmphasizes theft, disruption, loss, harm, or failure.
- 3
- Mitigation or actionEmphasizes protection, investigation, recovery, a fix, or limited scope.
- 1
- FavorablePresents an affirmatively favorable outcome for the selected company.
- 0
Sources checked 2026-07-22 · 1 archive copy
Price recovery
No initial drop
Here, recovery only means that adjusted close reached the baseline again. It does not mean every effect of the incident ended.
- State
- No initial drop
- Initial trough
- +6.3% on Jun 10, 2021
- Recovery close
- Not applicable / not observed
- Calendar days
- —
- Observation cap
- 24 months after disclosure
Hypothetical $1,000
What would $1,000 have looked like?
Compare $1,000 in FSLY with $1,000 in SPY, bought and measured on the same dates.
Entry Jun 11, 2021 Exit Dec 10, 2021
Uses fractional shares and adjusted close. Leaves out taxes, fees and slippage. The holding period starts on the purchase date. This is a historical illustration, not an investment strategy.
Case note
Fastly reported that an undiscovered software defect was activated by a valid customer configuration, causing 85% of its network to return errors. Monitoring detected the disruption within a minute and most service recovered within an hour.
The public status update occurred before the US market opened, so June 7 is the baseline and June 8 the reaction session. This is a quality and digital-resilience event, not a security breach.
Evidence
Sources and case review
We qualify each case before checking its price results. These links support the disclosure date, listing, incident and business impact.
- primary Jun 8, 2021Summary of June 8 outage Fastly Supports: Disclosure, Timing, Impact, Description
- primary Feb 23, 2022Fastly 2021 Form 10-K Fastly / U.S. SEC Supports: Listing, Impact
- Listing evidenceChecked Jul 20, 2026Fastly 2021 Form 10-K U.S. Securities and Exchange Commission Event-period SEC history confirms Fastly's NYSE listing under FSLY at disclosure.
Why it is included. Fastly was the responsible service operator; the defect disabled 85% of its network and disrupted many dependent digital services, meeting the systemic-outage threshold. Reviewed Jul 20, 2026.