Shares in Barclays PLC , one of the U.K.’s most prominent stocks, plunged 10% at the opening bell Wednesday and then recovered, triggering a trading halt and an auction process to sort out the messy activity.
Reasons for the sharp drop and subsequent rebound couldn’t immediately be ascertained, though a trading error was a possible cause, according to market participants.
“I have absolutely no idea what drove the move—it seemed very odd,” said Joe Dickerson, a banking analyst at Jefferies who follows Barclays.
A Barclays spokeswoman declined to comment.
The London Stock Exchange halted trading in Barclays shares under its rules to ensure an orderly market. An auction followed allowing investors to place orders to find the price that reflected the aggregate of buy and sell orders. That process, while unusual, applies to the biggest FTSE 100 stocks if they unexpectedly move up or down 3% or more.