The share prices of some the UK's best-known companies appeared to fall as much as 99 per cent Monday, after the London Stock Exchange (LSE) updated its tech over the weekend.
Blue-chip firms ITV, BHP, Shire and Rio Tinto were among a number of firms that appeared to have flash crashes in their share prices.
The LSE upgraded its trading technology over the weekend and City sources pointed to this being the most likely cause of the problems.
It is understood the problems were due to systems reporting trades in pounds rather than pence, following the tech update, which allowed traders to post trades in different currencies.
Meanwhile, ITV shares languished at around 1.5p for two minutes, around one-hundredth of the FTSE 100 firm's normal price.
The BBC was forced into apologising to readers on their online blog, saying the LSE was experiencing "technical issues that will not be resolved until tonight at the earliest".
The London Stock Exchange declined to comment.