Pivotal Research Group analyst Brian Wieser reiterated his negative view of Facebook Inc. FB, -1.73% Wednesday, writing that the social-networking giant is "exhibiting signs of systemic mismanagement" following a series of security and public-relations issues involving user data, content moderation, and political advertising. Facebook shares are down 2.3% in Wednesday morning trading, after falling 9.2% so far this week. "Investors have to consider whether or not the company will conclude that it has grown in a manner that has proven to be untenable or whether it needs to significantly improve how it is managed," he wrote. That leads to the possibility that Facebook could "depress the size of the company" or introduce personnel changes, both of which Wieser said present new risks to investors. Wieser is one of two analysts who rates Facebook at sell, and he has a $152 price target on the stock. The stock closed Tuesday at $166.31. Facebook shares are up 21% over the past 12 months, while the S&P 500 SPX, -1.15% is up 16%.