Costco (COST)
COST moved a median of -0.02% 30 minutes after news, and +0.00% by the close. How COST actually reacts to news — the realized, point-in-time move the market made, measured across 2,000+ labeled events over the last three years with zero look-ahead.
COST’s median reaction, across the day.
| Middle 50% of COST reactions | -0.42% to +0.30% |
|---|---|
| Median reaction (30-min) | -0.02% |
| Measured reactions | 2,000+ |
Half of all Costco news events land between -0.42% and +0.30% at 30 minutes.
Reaction stats as of 2026-07-14. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
How COST reacts, by analyst action.
| Event | Events | Median 30-min | % positive | Median to close |
|---|---|---|---|---|
| Analyst upgrades | 21 | +0.43% | 81% | +0.81% |
| Analyst downgrades | 28 | -0.45% | 33% | -0.54% |
| Coverage initiations | 25 | +0.08% | 64% | +0.28% |
| Rating reiterations | 342 | -0.04% | 47% | +0.04% |
| Price-target raises | 150 | -0.08% | 43% | +0.05% |
| Price-target cuts | 22 | -0.39% | 18% | +0.05% |
Last 3 years, pulled 2026-07-14. Reaction = percent move vs. the price at the news timestamp. Counts and medians only. The same measurement runs across every name in the dataset. See how COST ranks against every other measured name →
That’s how COST usually reacts — get an email when it moves on news →Email me when COST moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to COST's baseline. Nothing else.
Recent COST events, each with its measured reaction. (Page 1 of 3.)
Each headline opens its own page with the full realized reaction — the move the market actually made, measured from the news timestamp.
Where else COST is measured.
COST earnings → · Analyst actions → · SEC filings → · Full history →
Other Consumer Staples names, measured the same way
| Ticker | Events | Median 30-min | % positive |
|---|---|---|---|
| Coca-Cola (KO) | 2,000+ | -0.02% | 47% |
| Walmart (WMT) | 2,000+ | +0.01% | 52% |
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 Consumer Defensive names, measured the same way →
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Every name we’ve measured, in one place.
How the numbers are made.
How is Costco's median reaction calculated?
Every labeled COST 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 2,000+ 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. 48% of COST'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 2026-07-14.
Does COST'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.