• by Mark Walsh  @markfwal, September 11, 2012

Facebook CEO Mark Zuckerberg acknowledged disappointment with the company's stock performance since going public in May, but voiced optimism about its nascent mobile business as a long-term growth engine.

Speaking publicly on Tuesday for the first time since Facebook's botched IPO, Zuckerberg addressed a wide range of topics about the company before a packed hall at the TechCrunch: Disrupt 2012 conference in San Francisco. The most immediate issue is the social network's plummeting stock price, which has been nearly halved from its $38-a-share offering price.

Some analysts have suggested that Zuckerberg is overly focused on building products with little regard for Wall Street's focus on quarterly profits and growth. But the CEO suggested the company mission to “make the world more open and connected” doesn't conflict with achieving financial success. "Building a mission and building a business go hand-in-hand,” he said. “We need to do both.”

Asked about the impact of the depressed stock price on employee morale and retention, Zuckerberg admitted the steep decline “doesn't help.” But he said the company is not a stranger to controversy and outside criticism and will be able to weather the current difficulties it faces as a newly public company.

What's more, he argued that the drop in Facebook's stock price makes it a great time for new employees to join the company and existing ones to “double-down” and benefit from an eventual upswing in the value of their shares. One of the biggest questions feeding investor uncertainty is about Facebook's ability to monetize its mobile audience of more than 500 million and growing. The company only began running mobile ads in March, but Zuckerberg emphasized the huge potential that mobile offers for revenue growth.

"Over the next three to five years, I think the biggest question on everyone's mind, that will determine our performance over that period, is really how well we do with mobile,” he said. One of the key steps Facebook has taken in recent months was to ditch HTML5 in favor of building native apps for iOS and Android devices.

Zuckerberg called the company's bet on HTML5 its biggest mistake to date, acknowledging that the programming technology in the near future wouldn't be able to deliver the same capabilities as native apps. Facebook's recently updated iOS app has been well received and Zuckerberg said a new Android app is coming soon, without being more specific.

The CEO also reiterated that Sponsored Story ads running in the mobile news feed are performing better than the standard display ads that run on the right side of Facebook pages and generate the bulk of its revenue. Early results from outside ad firms this summer indicated that mobile ads were earning 2.5 times more than traditional ads.

"We're going to make more money [in mobile] than on the desktop," said Zuckerberg on Tuesday.

A forecast released by eMarketer last week projected that Facebook will make just 72.7 million in U.S. mobile advertising, but ramp up to $629 million by 2014. A far more bullish outlook from Doug Anmuth, an analyst at JP Morgan, one of Facebook's IPO underwriters, predicts the company will earn 200 million from mobile ads this year, and 900 million in 2013.

One mobile project Facebook won't pursue is a branded mobile phone. Zuckerberg denied repeated suggestions from interlocutor Michael Arrington that Facebook is building its own phone to compete directly with the iPhone and Android. Rather, he said it makes more sense for Facebook to work across multiple platforms to reach the widest mobile audience possible.

However, Zuckerberg didn't rule out competing more directly with Google at some point in search. “That's one obvious thing we could do in the future if we were excited about it,” he said, noting that Facebook already generates 1 billion queries a day. The company last month did introduce search advertising, allowing marketers to run Sponsored Results that direct users to a specific Facebook app, group, event, or brand page.

Did Zuck's talk do anything to reassure investors? In after-hours trading, Facebook shares were up 3.3% to $19.43. Not a strong vote of confidence, but better than hitting a new low.