Zuckerberg answers investors on Instagram and China - what's that about a Facebook slowdown?

Facebook shut out media from the event which was for investors and would-be investors only. So reporters gleaned what they could from "attendees" - people who had been queuing round the block in their hundreds at the Sheraton hotel beforehand but were willing to talk to reporters later.

The 27-year-old chief executive certainly didn't feel he had to dress up for the event: he wore his usual "hoodie" sweatshirt, jeans and sneakers.

Zuckerberg personally forged the deal to acquire mobile app maker Instagram in a matter of days last month, with according to the media, little involvement from Facebook's board of directors.

Asked about that by an attendee, Zuckerberg said Facebook's management had discussed a possible Instagram acquisition at length in several meetings.

Facebook decided to act when it saw Instagram's user data cross a "tipping point" from which they believed it would grow significantly, he said.

He said Facebook moved quickly to strike a deal when it became clear that Instagram was open to being acquired. He said he would do the Instagram deal again if he had to, according to attendees.

Zuckerberg's majority control has been an issue simmering in the background. The Instagram question brought it into the foreground. Zuckerberg will have roughly 57 percent voting control after the IPO.

With Zuckerberg was finance chief David Ebersman, who was wearing a suit and tie, and chief operating officer Sheryl Sandberg.

Investors managed to ask just five questions during the event. One was about Facebook plans - if any - to enter China, the world's largest Internet market

Zuckerberg noted that Facebook was blocked in China. Popular U.S. websites such as YouTube and Twitter were in the same boat.

Sandberg added that Facebook was willing to sit down with Chinese government officials and discuss partnerships in the country.

Reuters reported that Facebook's emergence as a cultural phenomenon as in the fictionalized 2010 film The Social Network "added a palpable level of energy and buzz to the event. One investor was overheard joking that the event should have been held at New York's Madison Square Garden, a standard venue for rock concerts." Still the buzz didn't help the early flow of information.

The first line from attendees: Morgan Stanley banker Michael Grimes began the formal presentation as the investors lunched on Cobb salad, ice tea and cookies, said attendees. Yes, it was that exciting.

As we went to press, we still hadn't heard what if anything Mark said about suggestions that Facebook was slowing down.

With 900 million users, Facebook is challenging established Web businesses such as Google and Yahoo for consumers' online time and advertising dollars.

The 8-year-old social network indicated an IPO range of $28 to $35 a share last Thursday, which would value the company at $77 billion to $96 billion.

But many investors say they expect Facebook to raise its offer price-range as the roadshow progresses from New York to major cities such as Chicago, Boston and San Francisco.

Let's hope the attendees have their notebooks opened and their pencils sharpened. If we hear any more from them today. we'll let you know.