Twitter may have had really bad earnings last quarter, but its cofounder and chief executive Jack Dorsey continues to believe strongly in the company. On Tuesday, Dorsey. tweeted “#LoveTwitter,” along with a link to an S.E.C. filing announcing that he’d bought $7 million in Twitter stock. The new shares Dorsey now owns make up about 3 percent of his Twitter holding overall. On Thursday, Twitter announced its fourth-quarter earnings for 2016. It missed analysts' expectations for revenue, and its advertising revenue bookings shrunk 1% year-on-year — sending its stock tumbling 10%.