Twitter rolls out new ad format that shows exclusive content

Twitter Inc. rolled out a new way of creating revenue this week with an "instant unlock card," that allows users to see exclusive content if they click a button to tweet with a specific hashtag. Twitter said AMC, for example, recently used the format to show users an exclusive trailer for the TV show "The Walking Dead" when they clicked a button to tweet. The move comes as Twitter reported its worst-ever revenue growth in its second-quarter earnings. Shares of Twitter have gained 28% in the past three months, compared to the S&P 500's gain of 5.5%

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