Facebook Chief Executive Mark Zuckerberg remotely rang the opening Nasdaq bell from the social network's California headquarters on Friday, kicking off the company's initial public offering (IPO), the largest ever for an Internet firm.

After a 30 minute delay as brokers tried to match large sell and purchase orders, the shares opened at $43 before falling back to $38 some twenty minutes later.

Facebook had announced on Thursday that it sold shares to investors for $38 ahead of the IPO. It had priced the shares at $34-$38. The company and its early investors could reap $18.4 billion, which would give it a market value of around $104 billion.

The IPO is the third-largest in US history, only surpassed by the initial public offerings of two Chinese banks.

Due to strong demand from investors, Facebook increased the price earlier in the week, which had stood at $28-$35, as well as boosting the number of shares it was selling by 25 percent to 421 million shares. Altogether it is floating 15 percent of its shares.

The pre-IPO sale makes the company worth more than Hewlett-Packard and Dell together.

Google had sold shares for $1.7 billion when it went public in 2004, valuing the company at $23 billion. It's currently valued at around $200 billion.

ncy, slk/jm (dapd, AP, Reuters)