Shares of U.K. bank HSBC briefly surged 9.8 percent in morning trade on Thursday, with market watchers blaming a trading error for the move.
At approximately 11.30 a.m. London time the lender's stock spiked nearly 10 percent before quickly falling back to resume its normal trading pattern for the session.
The brief move expanded HSBC's market capitalization by around £11 billion - to £129 billion from £118 billion. An HSBC spokesperson told CNBC they believed a trading error was behind the jump.
Traders and market analysts gave immediate responses to the spike on the social networking site Twitter. Will Hedden, a trader at IG Markets said: "(There are) some very fat fingers in FTSE land today."
(Read More: Dream run in US stocks set to end: HSBC)
His colleague, market strategist Brenda Kelly, told CNBC vie email that there appeared to be no news behind the sudden climb — and that a trading error appeared to have occurred.
"The push to 688p from 630p was very short-lived so it looks like a trader error that was very quickly reversed," she said. "Fat finger is the clear explanation."