Reuters: Twitter interim CEO Jack Dorsey joined other insiders in buying more shares in the company in a show of confidence in the stock, which traded at a record-low last week. Dorsey has been candid about the problems faced by the microblogging website. User growth in the second quarter increased at the slowest pace since the company went public in 2013. “Investing in @twitter’s future,” Dorsey tweeted, after disclosing he had bought 31,627 shares, worth about $875,000 at $27.67 per share.