What are the 5 most expensive bugs in the history of computing: here is the damage they caused

The world of technology is dotted with historic successes, but also with sensational failures. Errors in software design and development can cause bugs (software operating errors) which, in some cases, have generated damages quantifiable in hundreds of millions of dollars in economic losses. In this in-depth study, we present you with an overview of some of the 5 of the most expensive bugs in the history of computing: from the failure of Ariane 5 flight 501, to the most recent CrowdStrike Falcon Sensor software bug, through Intel’s FDIV bug, the millenium bug and the one affecting Knight Capital Group.

The 5 most expensive bugs in history
  • 1The failure of Ariane 5 Flight 501
  • 2The Knight Capital Group bug
  • 3The FDIV bug in Intel Pentium processors
  • 4The IT failure of the CrowdStrike Falcon Sensor software
  • 5The Millenium bug (or Y2K bug)

The failure of Ariane 5 Flight 501

The June 4, 1996the launch vehicle’s maiden flight Ariane 5 of theESA (European Space Agency) ended in historic failure. Only about 40 seconds into the flight sequence, at an altitude of about 3700 m, the launcher deviated from its flight path, broke up and exploded due to an error in the software system (which was trying to insert a 64-bit number in the space of a 16-bit one), causing damage estimated at least 370 million dollars (but according to other estimates the damage was much greater and amounted in total to 8 billion dollars). In the official report, still available on the European Space Agency website, in this case we read:

The Ariane 501 failure was caused by the complete loss of guidance and attitude information 37 seconds after the main engine ignition sequence was initiated (30 seconds after liftoff). This loss of information was due to specification and design errors in the inertial reference system software. The extensive reviews and tests carried out during the Ariane 5 development program did not include adequate analysis and testing of the inertial reference system or the complete flight control system, which could have detected the potential failure.

Model of Ariane 5 (real size) from the Cité de l’Espace in Toulouse. Credits: Poppy, CC BY–SA 3.0, via Wikimedia Commons.

The Knight Capital Group bug

A bug in the company’s trading software Knight Capital Groupin the’August 2012 caused the latter a financial disaster of biblical proportions. During a software update, a new feature broke, resulting in erroneous trades that destabilized the market. As reported by The New York Times in an article dedicated to the affair involving Knight Capital Group «the problem (…) led the company’s computers to rapidly buy and sell millions of shares in more than one hundred stocks for about 45 minutes after the markets opened. Those trades pushed up the value of many stocks, and the company’s losses appear to have occurred when it had to sell the overvalued shares back into the market at a lower price». In just 45 minutes, the company lost 440 million dollarsrunning out of capital and leading to its takeover.

The FDIV bug in Intel Pentium processors

The Pentium processor Of Intelreleased in 1994had a flaw in the floating point division operation or FDIV (Floating Point Division). It was discovered that some calculations produced incorrect results due to a bug in the lookup table used by the floating-point division circuit. Although the problem was rare, confidence in Intel processors was compromised, forcing the company to replace faulty processors, which cost the company approximately 475 million dollars. The incident, in addition to causing immediate damage to Intel’s finances, also scarred its reputation (at least at that time).

Intel Pentium 66 MHz (sSpec=SX837) with the FDIV bug. Credit: Konstantin Lanzet, via Wikimedia Commons.

The IT failure of the CrowdStrike Falcon Sensor software

Coming to the present day, the July 19, 2024an IT failure that affected the CrowdStrike Falcon Sensor security software it sent computer systems around the world into a tailspin, generating an IT blackout that brought various sectors to their knees, including international air transport, banking and even healthcare. The bug was caused by a software update error which, causing the computer crash, generated the famous blue screen of death on Windows systems. The damage due to the bug was estimated at 10-15 billion dollars.

The Millenium bug (or Y2K bug)

The infamous man deserves a separate discussion Millenium bugalso known as Y2K bugs. In the 1990s it was a global bugbear, generated by the practice – still very common in computing today – of representing years using the last two digits (for example using “99” for 1999). What was the bogeyman about? As the 2000 there was concern that computer systems might interpret “00” as “1900” rather than “2000,” which could cause widespread malfunctions in computer systems around the world. To be fair, the bug itself didn’t cause much actual damage, but companies and governments around the world spent an estimated 500 billion dollars (estimates range from 200 to 600 billion) to update systems and prevent possible disasters. Here, unlike the other bugs we have told you about, the expense was used for avoid the bug. However, we are talking about a really important figure!