In addition to research and prevention duties, EuSpRIG pulled together an extensive list of more than 80 public reports of spreadsheet errors from business, government and academia.

For both your sinister viewing pleasure and as a warning of what can go wrong without proper controls, here's a chronological list of eight of the more infamous spreadsheet transgressions, compiled from EuSpRIG, media reports and public documents, which are linked to at end of each entry.

1. Fidelity's "Minus Sign Mistake"

Lesson learned: Be sure to differentiate your gains from your losses, and have another employee review the work.
January 1995

"There was a big flap recently over Fidelity's Magellan fund estimating in November that they would make a $4.32/share distribution at the end of year, and then not doing so. A letter of explanation was sent to the shareholders...from J. Gary Burkhead, the President of Fidelity, including the following pertinent items: During the estimating process, a tax accountant is required to transcribe the net realized gain or loss from the fund's financial records (which were correct at all times) to a separate spreadsheet, where additional calculations are performed. The error occurred when the accountant omitted the minus sign on a net capital loss of $1.3 billion and incorrectly treated it as a net capital gain on this separate spreadsheet. This meant that the dividend estimate spreadsheet was off by $2.6 billion..."
—From the Risks Digest

2. The $24 Million "Clerical Error" at TransAlta

Lesson learned: Have another employee double-check the documentation.
June 2003

A simple spreadsheet error cost a firm a whopping $24 million. The mistake led to TransAlta, a big Canadian power generator, buying more US power transmission hedging contracts in May at higher prices than it should have.

In a conference call, chief executive Steve Snyder said the snafu was "literally a cut-and-paste error in an Excel spreadsheet that we did not detect when we did our final sorting and ranking bids prior to submission," Reuters reports.

This looks like a career limiting move by the person who made the cock-up and the people who failed to spot it. Snyder said the company would "deal with the individuals in the appropriate fashion if there is anything found. At the end of the day it's a simple clerical error."
—From The Register

3. Fannie Mae Discovers $1.3 Billion "Honest" Mistake

October 2003
Lesson learned: When billions are at stake, it's best to have a financial peer review the documentation.

Fannie Mae, which finances home mortgages, stated in a news release of third-quarter financials that it had discovered a $1.136 billion error in total shareholder equity. Jayne Shontell, Fannie Mae senior vice president for investor relations, explained in a written statement, "There were honest mistakes made in a spreadsheet used in the implementation of a new accounting standard."
—From PC World