Twitter shares slump as revenues dip and costs rise

Firm reports 'headwinds' as near 20% hike in costs and advertising bugs dent profits

Twitter shares slumped on Thursday after the social network reported lower than anticipated revenues and higher costs and said it expected advertising technology bugs to continue to drag on profits.

Shares fell by almost 20% in early trading on the New York Stock Exchange to a low of $31.10, the weakest since March.