Facebook rally fizzles as Wall Street still unimpressed Facebook stock is getting clobbered as the bears pile on. The stock, which has been under intense pressure since its initial public offering in May, took more hits on Wednesday. Analysts are urging caution over the company's mobile advertising business, which is considered vital to the company's growth. Another analyst cautioned that September's slowdown in desktop usage measured by research firm ComScore suggests that Wall Street's estimates are too high for 2013. And Bloomberg is reporting that regulators pressed Facebook to disclose additional risks related to its mobile and desktop advertising business days before the IPO. The correspondence between regulators and Facebook was already reported here in June. Bottom line: Wall Street is still not impressed with Facebook. Facebook has surrendered the gains it made after Facebook Chief Executive Mark Zuckerberg made his first public remarks last month. Those remarks, in which Zuckerberg made positive comments about the company's mobile ad business, pumped up the stock 24%, lifting it above the $20 mark. But on Wednesday Facebook shares fell nearly 3% to $19.72, one week after Zuckerberg announced the company had crossed the 1-billion-users threshold (and 600 million mobile users). That remarkable achievement was undercut by fresh concerns that Facebook cannot sustain that growth and may face challenges in profiting from its giant user base. The company that valued itself at $100 billion is now worth just a fraction of that as investors worry that Facebook is not making enough money fast enough or keeping up with its users' shift to mobile devices. Last year Facebook generated about $4 billion in revenue, mostly from advertising. Facebook hit 1 billion users which bodes well for revenue-mining opportunities from this vast group of users. But the next billion users will be much harder to come by," Michael Yoshikami, chief executive of Destination Wealth Management, told the Times. Facebook, in our view, is still a work in progress. One analyst remains bullish on Facebook. S&P Capital IQ's Scott Kessler noted that the past month has been "eventful" with Facebook closing its acquisition of mobile photo-sharing service Instagram and rolling out Facebook Gifts. We think the new product announcements demonstrate Facebook is focused on monetization. We believe the e-commerce opportunity is especially appealing, and see multiple opportunities," he wrote. We also have been encouraged by Facebook seemingly becoming more proactive and transparent in communicating about its strategy and products. Facebook is scheduled to report its third-quarter earnings on Oct. 23.