The encyclopedia · Finance & Accounting · Financial decision · 2003
A copy-paste error in a spreadsheet cost TransAlta $24 million in a power bid
TransAlta, a Canadian energy company, lost $24M when a spreadsheet copy-paste error corrupted its bid model for power supply contracts.
TransAlta · 2003
What happened
In 2003, TransAlta Corporation, one of Canada's largest power generation companies, was bidding on power supply contracts. The bid model was built in a spreadsheet, and during preparation a copy-paste error corrupted the data, causing the model to produce incorrect output.
The error went undetected through the review process. TransAlta submitted bids based on the flawed model, and the resulting miscalculation cost the company approximately $24 million — a significant sum for a single spreadsheet mistake.
The case became a widely cited example of spreadsheet risk in corporate finance and energy trading, illustrating how a routine copy-paste operation, combined with inadequate review controls, can produce losses far exceeding the simplicity of the error.
Why it happened
- A copy-paste operation in the bid spreadsheet corrupted the underlying data without any visible warning.
- The review process failed to catch the error before the bid was submitted.
- The bid model was complex enough that the corrupted output looked plausible to reviewers.
- No automated validation or reconciliation step existed to flag inconsistencies between the data source and the model.
The lesson
Spreadsheets fail silently. A copy-paste can corrupt a model with no error message, and plausible output fools reviewers. Validate at every data boundary.
Aftermath
The TransAlta case is cited in academic literature on spreadsheet risk alongside other famous spreadsheet errors (Salomon Brothers, JPMorgan's London Whale). It contributed to the growing field of spreadsheet engineering and the push for model risk management standards in energy trading and finance.
Sources
- TransAlta — Wikipedia (Canadian power generation company)
- Panko, R. 'What We Know About Spreadsheet Errors', Journal of End User Computing (2008)
spotted an error? The club wants to know.
More like this
JPMorgan's 'London Whale' lost $6.2B — and the risk model had a spreadsheet error
A ¥6.3B rescue couldn't stop a ¥23.7B writedown at China's mall giant
Gome's founder surrendered the company to a creditor for HK$377M
Somewhere, someone solved the problem this company failed at. 2nd Opinion →
Comments · 0
Sign in to join the comments.