TransAlta Corporation Ordinary Shares (TAC)
TAC moved a median of +0.20% 30 minutes after news, and +0.29% by the close. How TAC actually reacts to news — the realized, point-in-time move the market made, measured across 227 labeled events over the last three years with zero look-ahead.
TAC’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | +0.24% | 58% | 227 |
| 30-min | +0.20% | 56% | 227 |
| 60-min | +0.40% | 58% | 227 |
| to close | +0.29% | 56% | 226 |
| Middle 50% of TAC reactions | -0.81% to +1.25% |
|---|---|
| Median reaction (30-min) | +0.20% |
| Measured reactions | 227 |
Half of all TransAlta Corporation Ordinary Shares news events land between -0.81% and +1.25% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
How TAC reacts, by analyst action.
| Event | Events | Median 30-min | % positive | Median to close |
|---|---|---|---|---|
| Analyst upgrades | 27 | +0.61% | 59% | -0.22% |
| Analyst downgrades | 23 | -0.37% | 48% | +0.57% |
| Rating reiterations | 18 | -0.23% | 39% | -0.04% |
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 TAC ranks against every other measured name →
That’s how TAC usually reacts — get an email when it moves on news →Email me when TAC moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to TAC's baseline. Nothing else.
Recent TAC events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Form 6-K TRANSALTA CORP For: Oct 05 | SEC filing · Form 6-K | SEC EDGAR | -0.11% | -0.61% | |
| TransAlta to Host Third Quarter 2026 Results Conference Call | Press release | GlobeNewswire | +2.70% | +4.13% | |
| Department of Energy Mandates Centralia Unit 2 Remain Available for Operation for Additional 90 Days | Press release | GlobeNewswire | -1.13% | -1.59% | |
| Form 6-K TRANSALTA CORP For: Sep 14 | SEC filing · Form 6-K | SEC EDGAR | +0.51% | -2.71% | |
| Form 6-K TRANSALTA CORP For: Jul 31 | SEC filing · Form 6-K | SEC EDGAR | +0.70% | -2.95% | |
| Form 6-K TRANSALTA CORP For: Jun 30 | SEC filing · Form 6-K | SEC EDGAR | +0.70% | -2.95% | |
| TransAlta Reports Strong Second Quarter Results and Reaffirms Guidance | Press release | GlobeNewswire | +0.70% | -2.95% | |
| Form 6-K TRANSALTA CORP For: Jul 29 | SEC filing · Form 6-K | SEC EDGAR | -0.47% | +0.63% | |
| TransAlta Declares Dividends | Press release | GlobeNewswire | -0.47% | +0.63% | |
| Form 6-K TRANSALTA CORP For: Jun 30 | SEC filing · Form 6-K | SEC EDGAR | -0.66% | -0.51% | |
| TransAlta to Host Second Quarter 2026 Results Conference Call | Press release | GlobeNewswire | -0.66% | -0.51% | |
| Department of Energy Mandates Centralia Unit 2 Remain Available for Operation for Additional 90 Days | Press release | GlobeNewswire | -0.52% | +1.27% | |
| Form 6-K TRANSALTA CORP For: Jun 15 | SEC filing · Form 6-K | SEC EDGAR | -0.52% | +1.27% | |
| Form 6-K TRANSALTA CORP For: Jun 09 | SEC filing · Form 6-K | SEC EDGAR | +1.04% | -0.40% | |
| TransAlta Announces Closing of $350 Million Bought Deal Offering of Common Shares | Press release | GlobeNewswire | +1.04% | -0.40% | |
| Form 6-K TRANSALTA CORP For: Jun 05 | SEC filing · Form 6-K | SEC EDGAR | +0.83% | -1.42% | |
| Form SUPPL TRANSALTA CORP | SEC filing · Form SUPPL | SEC EDGAR | -0.69% | -2.08% | |
| Canadian Investment Regulatory Organization Trade Resumption - TA | Press release | Canada Newswire | -0.15% | -1.52% | |
| Form 6-K TRANSALTA CORP For: Jun 03 | SEC filing · Form 6-K | SEC EDGAR | -0.15% | -1.52% | |
| Canadian Investment Regulatory Organization Trading Halt - TA | Press release | Canada Newswire | -0.15% | -1.52% | |
| Form SUPPL TRANSALTA CORP | SEC filing · Form SUPPL | SEC EDGAR | -0.15% | -1.52% | |
| TransAlta Announces the Acquisition of Two Fully-Contracted Gas Assets in Colorado and Concurrent $350 Million Bought Deal Offering of Common Shares | Press release | GlobeNewswire | -0.15% | -1.52% | |
| Form 6-K TRANSALTA CORP For: Mar 31 | SEC filing · Form 6-K | SEC EDGAR | -2.05% | +0.63% | |
| Form 6-K TRANSALTA CORP For: May 06 | SEC filing · Form 6-K | SEC EDGAR | -2.05% | +0.63% | |
| TransAlta Reports First Quarter Results and Reaffirms Annual Guidance | Press release | GlobeNewswire | -2.05% | +0.63% | |
| Form 6-K TRANSALTA CORP For: Apr 30 | SEC filing · Form 6-K | SEC EDGAR | -0.40% | +0.08% | |
| Form 6-K TRANSALTA CORP For: Apr 29 | SEC filing · Form 6-K | SEC EDGAR | +0.50% | +3.23% | |
| TransAlta Corporation Announces Results of the 2026 Annual and Special Meeting of Shareholders and Election of all Directors | Press release | GlobeNewswire | +0.08% | -0.08% | |
| TransAlta Declares Dividends | Press release | GlobeNewswire | +0.50% | +3.23% | |
| Form 6-K TRANSALTA CORP For: Apr 20 | SEC filing · Form 6-K | SEC EDGAR | -0.63% | +0.08% | |
| TransAlta Appoints Mike Politeski as Chief Financial Officer and Grant Arnold as Chief Commercial Officer | Press release | GlobeNewswire | -0.63% | +0.08% | |
| Form 6-K TRANSALTA CORP For: Apr 07 | SEC filing · Form 6-K | SEC EDGAR | -1.57% | -1.00% | |
| TransAlta to Host Annual and Special Meeting of Shareholders and First Quarter 2026 Results Conference Call | Press release | GlobeNewswire | -1.57% | -1.00% | |
| Form 6-K TRANSALTA CORP For: Mar 12 | SEC filing · Form 6-K | SEC EDGAR | +0.35% | +0.73% | |
| Form 6-K TRANSALTA CORP For: Mar 23 | SEC filing · Form 6-K | SEC EDGAR | -2.70% | +1.43% | |
| TransAlta Investor Day Highlights Solid Foundation and Attractive Growth to 2029 and Beyond | Press release | GlobeNewswire | -2.70% | +1.43% | |
| Department of Energy Mandates Centralia Unit 2 Remain Available for Operation for Additional 90 Days | Press release | GlobeNewswire | -0.75% | -1.35% | |
| Form 6-K TRANSALTA CORP For: Mar 17 | SEC filing · Form 6-K | SEC EDGAR | -0.75% | -1.35% | |
| TransAlta Corporation Announces Conversion Results for Series A and B Preferred Shares | Press release | GlobeNewswire | -0.75% | -1.35% | |
| Form 6-K TRANSALTA CORP For: Mar 02 | SEC filing · Form 6-K | SEC EDGAR | -2.06% | -1.49% | |
| TransAlta Corporation Provides Conversion Right and Dividend Rate Notice for Series A and B Preferred Shares | Press release | GlobeNewswire | -2.06% | -1.49% | |
| Form 40-F TRANSALTA CORP For: Dec 31 | SEC filing · Form 40-F | SEC EDGAR | +2.72% | +1.03% | |
| Form 6-K TRANSALTA CORP For: Dec 31 | SEC filing · Form 6-K | SEC EDGAR | +2.72% | +1.03% | |
| Form 6-K TRANSALTA CORP For: Feb 27 | SEC filing · Form 6-K | SEC EDGAR | +2.72% | +1.03% | |
| TransAlta Enters Memorandum of Understanding for Data Centre Development at Keephills Site with Potential to Scale Up to 1 GW | Press release | GlobeNewswire | +2.72% | +1.03% | |
| TransAlta Reports Fourth Quarter and Year End 2025 Results, Announces Data Centre Agreement, Declares Dividend Increase and Provides 2026 Outlook | Press release | GlobeNewswire | +2.72% | +1.03% | |
| TransAlta to Host Investor Day | Press release | GlobeNewswire | +2.72% | +1.03% | |
| Form 6-K TRANSALTA CORP For: Jan 27 | SEC filing · Form 6-K | SEC EDGAR | -0.22% | +0.65% | |
| TransAlta to Host Fourth Quarter and Full Year 2025 Results Conference Call | Press release | GlobeNewswire | -0.22% | +0.65% | |
| Form 6-K TRANSALTA CORP For: Dec 22 | SEC filing · Form 6-K | SEC EDGAR | +0.32% | +2.01% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the TAC section they belong to.
Where else TAC is measured.
TAC earnings → · Analyst actions → · SEC filings →
Other Utilities names, measured the same way
| Ticker | Events | Median 30-min | % positive |
|---|---|---|---|
| Enel Americas S.A. American Depositary Shares (ENIA) | 232 | -0.06% | 41% |
| Companhia de saneamento Basico Do Estado De Sao Paulo - Sabesp American Depositary Shares (Each repstg 250 Common Shares) (SBS) | 227 | 0.00% | 50% |
| PENNON GROUP PLC UNSP/ADR (PEGRY) | 226 | 0.00% | 20% |
| American States Water Company (AWR) | 218 | -0.01% | 45% |
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 Utilities names, measured the same way →
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Every name we’ve measured, in one place.
How the numbers are made.
How is TransAlta Corporation Ordinary Shares's median reaction calculated?
Every labeled TAC 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 227 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. 56% of TAC'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 TAC'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.