HSBC shares spiked 10% in what's being called a "fat finger" moment on the FTSE 100Reuters

A "fat finger" has been blamed for causing a sudden spike in HSBC's share price, which quickly corrected itself again after leaping 10% out of the blue.

Market watchers and professionals were left scratching their heads when HSBC jumped, dragging the sluggish FTSE 100 into the black, before flattening back out again.

Most put it down to a trader's chubby digit hitting the wrong keys.

Others doubt that it was a fat finger, however.

HSBC fat finger
HSBC's "fat finger" spike in its share priceGoogle Finance